-bolter is now some kind of handcannon? 28 TU for aimed shot? Isn’t it a bit too much? And only 2 rounds?
Some kind of cannon, more like. IIRC the fluff always had it as a high-tech successor to the Sniper Rifle; it's just that now the stats bear that out. That said, 28 TU may be a tad steep.
-heavy laser seems to me inferior compared to plasma rifle. In every way. Less damage, same spread, high range is not really so useful, requires a lot of research
Laser weapons in general got excessively nerfed. There's a plan going on to make them a later-game anti-alien-armor weapon, and I'm also working on a weapon analysis and comparison tool to help balancing.
-plasma blaster seems now to be useless. Only 35 damage? It’s good for unarmored targets only.
30±5 damage, actually. It's really all about the Ball firemode at the moment.
-grenade launcher without multiply shots is not worth using. I think that handgrenades are better.
You're ignoring the major increase in range and the increased damage which, though it doesn't look very large, pushes GL grenades at nearly point-blank range solidly into one-hit-kill territory. Three-shot mode was critical in 2.4 mostly because it would almost certainly take at least two grenades to actually kill your target.
As for hand grenades, they've got better radius, TU use, and minimum inventory investment but substantially worse range, decently worse damage, and take up more space per shot ammo-wise; I don't think they really compete.
~J