Because now you don't need to fight at long range. You can just move your blob around to chase wipes, because one of the effects of this change is that Tommies will be much better at wiping squads on the retreat.
That's just not how tommy blobs function.
Again. Tommy blobs were strong because they sat and fired from max range (and had good durability, but that's already addressed). They were the best at this because they had the best long range DPS of any core squad in the game. This ideal use case is why they were strong.
Now you're suggesting that they're not going to be used at max range, and are going to be used aggressively to close in. In this use case, they are simply worse than volks and riflemen.
A moving tommy blob is worse than a moving volks/riflemen blob. Having a moving tommy blob means entirely giving up on the reason why tommies are blobbed in the first place.