Whoever says that powertechs/vanguards are not op either plays one and therefore doesn't want the class to be nerfed, or has no clue about what he's talking about.
1- Insane damage burst
2- Good utility, pull (you can say 45 secs cd, gets affected by resolve, it's still good), stun, aoe stun, interrupt
3- squishy but you can have your shield back pretty quickly
4- Not affected by interrupts
5- 2 powertechs targeting the same guy is something insane (you can say that is valid for every class, however no other class has got burst damage as good as they do)
If you think this class has got many weaknesses or is not op, then I encourage you to play commando/merc with the same spec.
1- Mediocre burst (you get 60% less armor pen than powertechs/vanguards)
2- Crap utility
3- squishy but you can have your shield back pretty quickly
4- affected by interrupts
5 - 2 hitting the same target really doesn't kill him fast
The reason why no one complains about assault commandos/pyro mercs is because that spec is mediocre for them.
The reason why everyone complains about powertechs/vanguards is because that spec is op for them for the differences I stated above.