That's exactly my point. These alien characters all tend to have something very Human that audiences can relate to. Most alien races in Trek represent an aspect of Humanity--either past or present--for good or for ill.
And I see nothing wrong with that, and it would make them excellent series leads.
I would argue that an alien series lead will probably have to carry a major aspect of the Human condition. It doesn't matter if the character is Vulcan, Klingon, or Nashiran. there's probably going to be a lot in that character that we see in ourselves or maybe even want to be in real life.
I know I would watch the hell out of a Kira series.
Ah, OK. Although fantasy rabbits aren't really the same as extraterrestrials, there's clearly an enormous overlap. And we're not talking fantasy rabbits interacting with a lot of human characters, are we?
Nah, the rabbits in Watership Down were fairly rabbit-like and never interacted with humans, though the show, from what I remember, did kiddify them a bit more and well...there are some mild fantasy elements (such as precognition) in all incarnations of the franchise. They, for example, couldn't get their heads around why a boat could float on the water and they never used technology or anything like that. And humans were always portrayed as this unknowable force who's actions are difficult to interpret for the rabbits and other animals. The most human aspect of the rabbit characters is probably that they have religion. But again, the aliens in Star Trek are very "human", more so than the Rabbits in Watership Down, I'd say.
Also I never said that there was overlap between rabbits and extra-terrestrials, just that narratives carried by non-human characters are possible.
I edited in a few additional remarks to my previous post that address this point. I can't agree that this necessarily follows, because the premise of a TV show must be sustainable over multiple episodes, except in the case of a limited series, in a way that a movie is not.
Maybe not with everything in a book, that is true, but I think an alien lead after the fashion of most alien Star Trek characters would be more than doable. As I said, I would watch a show with Major Kira in the lead.
Or a Data series, for that matter, I sure as hell can relate a lot more to Data than I can to Riker, a character I can't relate to at all.