I don't think it's a klingon thing or even an STO thing. I think it's an MMO thing.
What i mean is that way back at launch, engineers were billed as the tanks, sci as healers, and tacs as dps. Those who have played for a while know that the mmo trinity doesn't really apply but to an outsider, following those archetypes is the path of least resistance so to speak.
Now in all my mmo experience, dps classes have always outnumbered tanks and healers and most mmos are geared to that end. Just look at WoW. A 5 man dungeon is balanced for 1 tank, 1 healer and 3 dps. So given all the above, it's really no big wonder why tacs are everywhere.