1. Sappers get wiped from repairing it and the unit inside bleeds from being shot at, so it does have a reinforcement cost in practice
2. It has two mortars that are less cost efficient than two normal mortars. It outranges other mortars (only by 9 if you compare barrages) but other mortars can move to always be in range.
3. It can't move, so it will do less damage overall unless the battlefield stays in one place (which it may well do on bad maps like rails & metal, road to kharkov etc. but still)
I know I have said this before, but does being negative cause anything to change? I understand how people have the right to express their opinion on the forums, but these aren't new points and people have been complaining since launch. This game, since release, has been a roller coaster of high expectations and average payoffs. If we stop expecting the second coming of Jesus fucking Christ then maybe we can find patches and releases adequately exciting.