And regular Star Trek isn't guilty of that? :|
I mean, most Trek Federation ships have the same two layout (saucer+cigar+engines or saucer+engines), just differing greebles. Sure the Connie Refit and a Galaxy look modestly different, and the exact proportions are different, but they've got the same general layout. Plus in normal Trek (TOS to VOY) you're seeing over a hundred years of ship designs, while Star Fleet most of the ships (and not just the Federation) cover a period of only a couple decades (exception: The Texas OCL, which is over a hundred years old by the General War shows an earlier design style with modern engines slapped on, and the Romulans have a stark contrast between their decades old Eagle series and the brand-spanking-new Hawk series).
Normal Trek's Klingons are even worse, they also have only 4 ships!
The
K'tinga/D7, the
BoP (the most hilariously inconsistent ship in star trek), the
Vor'cha, and the
Negh'Var. And they all share the same general layout, and the Negh'Var is basically an enlarged Vorcha with some extra stuff stuck on (the TNG model makers pretty much just ripped half their Vorcha model apart to build the Negh'Var model).
Cardassians, 3 main ships, the little
Hideki, the
Galor, and the
Keldon, and the Keldon is a Galor with some extra bits stuck on.
The Romulans are a bit more varied in look but also only 4 ships,
Warbird,
D'deridex,
Scout thingie,
That Ship from Nemesis, but ironically I'd honestly say that if you dig into the fluff the Star Fleet Universe Romulans are far better developed than the Romulans ever were in normal Trek (which is one of my biggest regrets in Normal Trek, if they had gotten half the awesome development the Cardassians did...).
Dominion only have a few ships as well, same with the Borg.
I understand if you don't like the 60s style TOS
aesthetic. However, I do not understand the perceived lack of
variety compared to normal star trek. The only really varied group is the Federation (who are, of course, the main characters and get the most development) and even then the majority of Federation ships come very different generations ship design and service but use the same 2 "generic" layouts as well.