What happened to all the 'human' aliens?

[The Laughing Vulcan]

In terms of production, it was the advent of prosthetic make-up that made the forehead of the week alien a constant after, say Season 3 of The Next Generation and of course the movies following The Motion Picture, and races like the Klingons and Romulans were retconned-ish into developing bumpy heads.

But when Kirk's Enterprise would find aliens on a weekly basis who basically looked human in a different Theiss costume, and almost the same in the first couple of seasons of The Next Generation, it does raise the question as to why we didn't see again, races like the Sigma Iotians, the Eminians, the Argelians, the Fabrini, the Capellans, the people of that Roman planet, the Ligosians, or even the people of that Justice planet.

Will we see 'human' aliens again any time in Star Trek, and will there be an explanation as to why there are so many such aliens, the way Enterprise eventually explained the TOS Klingons?

 

[Pumpkin Bread]

We have Betazoids, El-Aurians, and Lanthanites.

 

[B.J.]

I really doubt we'll see any new indistinct-from-humans aliens without a story reason for it. It just raises more questions than the writers are interested in answering, and would tend to pull attention from the story they're trying to tell. Plus it would just look lazy these days.

 

[Tribblesonmars]

I thought there was an episode of TNG that explained why there were so many humanoid aliens? Something like an ancient race that seeded the galaxy?

 

[Mage]

I thought there was an episode of TNG that explained why there were so many humanoid aliens? Something like an ancient race that seeded the galaxy?

Sure, but that's humanOID. OP means basically looking like a human but with a weird costume.