Brainless blobs who act intelligent are impossible, because you can't have intelligence without a brain.
And yet, that's exactly what the main enemy in this game is - an intelligence without a
conventional brain.
***
The sniper rifle should become obsolete just as much as any of the other human weapons, even if a perfect head-shot from the original would kill an any alien every time.
On the battlefield, if given the choice between a sniper rifle that needs a headshot or a high tech rifle that can still do headshots but also has more chance of punching though the chest armour of an alien that's just run around the corner at you, the high tech choice will naturally take precedence.
A pure sniper version of the Bolter rifle would be a good starting point, and would stop that research being such an instant dead end given that laser research (which allegedly makes bolters obsolete) can be started at exactly the same time. Built for accuracy it could be nearly as accurate as the laser rifle but with more one-shot stopping power.