Seems the issue is not about DPV then but burst damage. Something a Cruiser is not designed to do easily for a reason.
Burst damage is ironically excactly where beams are strongest: Beam Overload powered by weapon battery -> Ouch.
Well, that and Tactical Captain abilities, those make a huge difference, closely followed by Science (if good Sub-nuke timing ...). It's just Engineers that lack punch, but they can instead survive such a burst, no reason to complain.
And before we get started on BOff abilities, let's not forget that Cruisers have the one big equalizer here: EPtW. Every other ship type has to choose between being a glass-cannon, or suffering heavy drain - Cruisers can have thier pie and eat it, too.
I'll not deny that Escorts can deal more damage than Cruisers - but the gap beween even the lowliest Cruisers in terms of dps (Star Cruiser, Galaxy-R), or Science Ships for that matter, and the best DPS Escorts isn't more than 50% - and there's quite a lot of Cruisers in the middle of the pack, and Battle Cruisers (including the Galaxy-X, btw(!)) are very near the top.
Oh, and then there's Carriers. Those really are OP. But nobody cares about them.