Trek at least has a good reason for humanoids being all over the galaxy.. essentially evolution was deviated that way on each world that gave rise to them. Seems to imply that intelligent life would have been rare, though not unknown on worlds they did not tamper with.As much as I don't want to delve in to the timeless battle of Star Wars vs. Star Trek (though, I think SF Debris already ruled in SW's favor, at least for the wikis), Star Wars is not a good comparison. The main reason is that as much as I like SW the technology is very stagnant. That is neither realistic nor a good benchmark for me to compare.
Regardless, I am of the opinion that all speculative fiction (science fiction & fantasy) needs to work on more diversity among races of aliens or fantasy creatures. This includes both Star Trek and Star Wars and I think both franchises are lesser for not having the diversity of current races but instead just adding more aliens.
I too though would like to see more alien aliens. Bring on the Tholians. And it would be fun to see the Breen turn out to be folded up strange mantis's that look nothing like humanoids at all.