I don't disagree that GW could, and probably should, provide a better framework for more creative maps and scenarios. But a HUGE aspect of all Warhammer games for decades has been their group/convention/tournament play. You often need those games to be more "generic" so the playing field is more "balanced." GW probably does focus too much on the tournament aspect of their games and not more like roleplaying games, which provide a framework for different kinds of play with at home games.
There are some battleplans that are very unique, but they're usually in the battletomes or White Dwarf articles and never used widely or tournament legal. You're right that the tournament aspect requires them to focus more on balance than on interesting gameplay. Hence why most objective layouts typically have 2 objectives close to each player's starting territory, and 1-2 more in the middle of the board for them to fight over. This tends to keep the VP score from getting too lopsided early in the game but nearly always leads to the "camp this one spot on the map" style of gameplay I was talking about before.
Personally, I'd be very interested in seeing how AoS plays with getting rid of most objectives altogether. Instead of scoring by sitting on a specific spot on the map, you could score points by completing more gameplay objectives. So have more battle tactics and more varied options for battle tactics, and have more and better faction-specific battle tactics. I'd make the faction-specific ones worth more points than the universal ones. Then your faction's battle tactics would be something that the opponent would have to know and they somewhat dictate how your army would play. Perhaps the game would feel more like a battle of trying to counter your opponent's tactics while trying to execute your own instead of having a general meta tactic like "rush your opponent in their deployment zone" or "sit your guys on the circle longer than your enemy's guys."
But, since AoS is more of an upscaled skirmish game, as opposed to a mass battle game, Skinks will likely need something else to see the field. Maybe it's just making them cheap enough? Maybe 20/40-sized units could do it? Maybe a better special ability (although two chances at a good redeploy isn't terrible)?
Personally I believe Skinks belong at the 20/40 unit size as they are now. If you wanted to keep them at the 10/20 unit size, either their shooting or melee needs to be better. With a lot of stuff having at least -1 rend in 4e, anything with rend pushes Skinks to no-save territory. Having a 5+ save from shields or having a better shooting profile while also being at a 20-40 unit size for like 120-150pts for the unit would make a lot more sense and also give them a better defined role in the army in my opinion.
Let's compare Skinks to our mortal enemy's similar unit, the Clanrats: The rats have a 20 MSU, the same melee profile as Skinks with 2 attacks instead of 1, but no shooting. They have a 5+ save instead of a 6+, are slower but have much better keywords and abilities. They have built in d3 unit recursion, better CS with the standard bearer, and a better chance to rally if they try to do that. The only keywords Skinks have are infantry and a champion. At a reinforced unit of 20, Skinks are 180 points, 30 points more than a MSU of 20 Clanrats. So Clanrats are better screens, better at holding objectives, better at lasting longer in combat and server the "cheap bodies" role much better. Oh, and they have auto-wound crits as well.
The only special ability Skinks have is to roll twice to redeploy. Getting a better chance to redeploy would be ok if their purpose was still ranged skirmishers but they do next to no damage even to the squishiest of targets so trying to use them as skirmishers is almost pointless. Personally I'd prefer seeing them as squishy but fast ranged infantry that actually can do a little bit of damage at the very least. Especially since they are able to shoot in combat.
To be honest, I don't think the problem would be the maps. It's the way GW designs factions to be extremely assymetrical. A full flying army for example, would be ridiculous on a map with a chasm. Similarly, something like a knight army would probably end up feeling rather weird.
That's definitely one of the main issues with balance in AoS in general. On the one hand, it's awesome to have armies with specific and unique themes and playstyles. KO and their flying boats, Nighthaunt's flying, speedy ghosts that scare you on the charge, Tzeentch being magic focused, Idoneth riding sharks, eels and giant turtles, etc.
But on the other hand, when armies have such radically different playstyles and unit types from other armies, you definitely end up with a bit of a "rock, paper, scissors" scenario where one army tends to absolutely overwhelm specific armies but get curbstomped by others. Sometimes you have really blatant balance issues like when Gargants were introduced with their 35 wound "DPS check" that some armies couldn't make, or Lumineth being absolutely awesome at *everything* when they were added and being able to beat just about any army in any phase the majority of the time. But I think a lot of armies that actually have the ability to play multiple playstyles get shafted the most. I'd say that Stormcast, CoS, Skaven, and Seraphon all have enough variation in their units to be able to run your traditional "mixed arms" force that you'd see in games like old Warhammer but AoS doesn't support that kind of play. If you removed objective control as the main focus of gameplay, I think you'd be able to see a lot more varied playstyles using a lot of these units that don't ever get much time on the table.
Unfortunately the solution that often gets looked at most is either nerfs that are too heavy-handed or the overall trend of simplification and stripping out all the flavor and fun from armies to make them more similar to each other for the sake of balance. I'm honestly not sure what I would do to balance the game without doing either of these things, but at the very least I think that they should put more effort into armies' internal balance and making all their units have a viable reason to be used in game.
While the ability isn't "bad", it isn't fun. And more importantly, it still doesn't allow them to actually do anything.
To be honest, they should just get the Hunters of Huanchi bolas rules (and then GW can fix the Hunters of Huanchi while they're at it...). Then they'd at least have some value beyond merely standing in the way of things.
Personally I'd give them back a poison-themed rule. Either crit: mortals, crit: auto-wound or maybe a poison ability that goes off if they do any damage and it reduces the target unit's save or something...
Having played several games of 4th ed, I disagree that one "basic" hero could destroy an army's worth of Skinks, or maybe even a single unit of them right away. I consider a basic hero to be a cheaper foot hero, like our Oldblood, for example. I assume this is hyperbole to try and make your point. I've had a unit of 5 Chameleons survive small units of knights, small units of troops, and basic foot heroes. Yes, a bigger mounted hero or one on a monster could do much more.
If you're talking a basic unit of 10 Skinks, against any "standard" melee foot hero they should at least last 1 combat phase. It's hard for a foot hero to do 10 damage in a single combat phase unless they've got a lot of special rules. For example, a Clawlord could feasibly *maybe* do 5 damage to a Skink unit and would probably take 0 damage in return. But the Light of Eltharion could easily wipe 10 Skinks in a single combat phase and probably could take out an entire army's worth of Skinks in a few turns. But yeah, foot heroes in the 100-150 point range aren't going to solo 40 Skinks or anything like that.
