Modularity isn't the issue. It's an idea, and one that makes some sense, but Starfleet appears to be the only power in that uses it. We've never seen aliens use it the same extent (Galaxy and Nebula, Constitution and Miranda, use near identical parts) or use modular separation. They're all too cool, I guess.
Well, the Cardassians show very little difference between the
Galor and
Keldon classes, with the baseline hull designs being largely the same between the two and the latter having more superstructure, armor and weapons. There is also a similarity in style between the Klingons'
Vor'Cha and
Negh'Var designs, which are natural progressions from the
K'T'inga (of which the
Kronos One is, of course, a subset), which evolved from the
D-7, which evolved from the
D-4. It was the Bird of Prey designs that were outliers in the Klingon Fleet, and that's only because the design in question was originally supposed to be Romulan, but a similar design lineage was created for it in
Enterprise in the form of the
22nd century BOP and
D-5 (which could be seen as a hybrid between the two). And even ships in the JJ Abrams alternate universe share and preserve similar design aesthetics from organization to organization - all Federation ships and Klingon "
Warbird", for example. The Hirogen
Hunter and
Dreadnaught use seemingly identical components, and damn near ALL the Vulcan ships shown in
Enterprise (pre-Federation) shared the same general design layout with the ring-shaped warp engines and color palette (indicating the same kind of metal used for hull construction). And those were just the ones I was able to quickly find off the top of my head - I'm sure there are more. So it's hardly just a Federation trait.
Now, if you want to talk about the ridiculous overuse of something, the ubiquitous and limited naming of Klingon and Romulan ships in the form of "Warbid" and "Bird of Prey" has always frustrated the hell out of me. Klingons do not have the same reverence of birds that Romulans do, at all. There's no reason to call Klingon ships these same names, despite any sharing of technology they may have had over the years. Hell,
Enterprise showed that the Romulans started off at Vulcan "marching under the banner of the Raptor's wings", or something like that. That was
their thing, not the Klingons. They even also made a Klingon "
Raptor" at one point, too. Feh! That, to me, is a far more idiotic example of overuse than design layouts and palettes. The former is lazy and muddied writing - the latter has its roots in real-world ship design and modern construction principles.
And, to be a bit meta, Star Trek is about Federation crews. For this fact alone it stands to reason we would always see more Federation ships with the same design sensibilities than aliens of the week.
