Star Wars

One of the true unforced errors of the Disney era, particularly the ST itself. I get that they didn't want to be "MCU, Space Opera Division," so they wanted to get a little auteur thing going on and let JJ et al do their own thing, but Lucas et al created literally dozens of aliens and for the most part none of them were in the ST, even in background roles. It made it feel disconnected. "The universe is too small" has also been a fair criticism, but (1) you don't fix that all at once, and (2) they didn't really do that anyway, just made all the aliens into pufferfish or catfish.