Oversize the combadge, tweak the collar, oversize the rank pips (and make them independent of actual rank). Toss in Vulcan/pointed ears usable for all races.
Because it's phony, any faction can wear it..
There's a certain appeal, I think, to a uniform that encourages you to "be bad" and impersonate a higher ranking officer, a Vulcan, or another faction. And the pointed ears unlock, much like the Seven of Nine Borg bits, are a great RP costume addition for anyone who roleplays a hybrid or wants to look Vulcan for the day.
I have to admit, I don't see the point. First off, why should a Starfleet officer or KDF warrior wear a phony Starfleet uniform? Okay, I could see the Syndicate trying something like that, but why would the fake version differ that much from from the real one? That'd be both counterproductive to the original intention and not really reasonable, given that the factions' knowledge of each others' uniforms is not based on hearsay but actual contact and archived images.
And "clothing" that gives you the appearance of another species? Really? Why do we have the different species that are in the game? Just for the stats?
I'm not sure I want to see "elf ears" become a fashion trend in STO. The population of ESD already looks weird enough.
What I'd rather see for "neutral" clothing unlocks would be clothes or items that actually make sense to be used by (potentially) everyone. But instead of entire dresses it could be a "pack" of individual items to mix-and-match with existing stuff. New boots, pants, belts, backpacks, "cosmetic gear" that is worn on the character ...
And yes, apologies for being the party pooper here, but it is hard for me to understand why it's not enough to play within the scope that our factions already offer. Has space become that boring, for real?