IMO people are exaggerating how big of an impact it will have on the game, if the enemy garrisons it. I can understand getting sad if you read the rules for the terrain piece and expected to use the D3 MW terrain zapping feature from turn 1 every game, but I honestly think it would be a bit too good if we got it every game for granted and could tailor a list around it. The D3 alone might not be crazy, but when you couple it with Comet's Call and potentially other Endless Spells/normal spells it starts to stack up fast. Alot of enemies would have their terrain denied since support heroes are likely dead turn 2.
The opponent dumping some support heroes or whatever inside can very quickly turn into a trap for them. Not only is said model(s) suddenly MUCH harder to screen since the Engine has a huge footprint, it also makes it very easy to dump MW at it with spells etc. Cover and -1 to be hit is great, but it doesn't make the model(s) immortal by any stretch.
Heavy Saurus lists might not have the resources to turn it into a trap, in which case you might want to think differently about the terrain piece. It can work as a piece that blocks LOS for your Saurus heroes etc. while they buff units around them - They dont need LOS to activate their command abilities. You could have a Carno sit out of harms way, then give it fly and 3D6 charge etc. to suddenly pick a desired fight.
There are honestly loads of ways to use it. Straight up saying it's worthless is just not right.