^But it doesn't make sense, since the Borg Collective is, well, a collective. Every drone throughout the galaxy is controlled by a single collective consciousness. There are no separate "nations" within it, just a single homogenized whole. Yes, assimilating a new species would theoretically add some new elements into the mix, but with so many thousands of species in there already, it would be diluted to a homeopathic degree (well, not quite homeopathic, since at least there'd be some
actual trace of it present). It wouldn't significantly change the whole in any noticeable way, and any subtle change that did occur would be uniform throughout the entire Collective.
Especially given that the Borg are complete hypocrites. They claim to welcome new distinctiveness, but they're the ultimate conformists, ruthlessly suppressing and expunging anything that doesn't fit their preconceived notions of "perfection." So they probably discard all the really novel and distinctive traits of their assimilated species and just keep the stuff that's pretty much the same as what they already have.