They needed the Token ethnic human. Tuvok was black but an alien.
[At risk of legitimizing this flippant accusation with genuine argument...]
And what was Chakotay, sliced bread? B'Ellana too? Tuvok was also the first black Vulcan, a role of primary importance, which I think counts for something. That's 3 main characters of 9; granted a minority, but 33% distribution. And I'm not even counting the fact that VOY had a female captain, another first. I don't think that's a token. It may not be an even distribution (show me a place that has one and I'll show you a racist policy). But it's hardly dismissable as tokenism.
Racism is an issue worthy of examination and serious reflection; a lot of people have a legitimate argument of feeling marginalized by majority cultures. Yes. Yes. And not excluding caucasians.
But I'm afraid I don't quite subscribe to the accusation of tokenism. Why is it that being diverse is interpreted as "tokenism", while not being diverse would certainly be labeled racism? Should there be a majority of minorities on the bridge? That, I'm afraid, would also be tokenism and hypocritical, in that the majority culture would be removing itself from the equation, as if from a position of "objective, value-free superiority".
Serving all other cultures except one's own - is also discriminating. It is to be blind to one's own cultural heritage, values and biases. It's as bad as excluding all other cultures.
There is no reason why a majority culture should not represent itself as a majority in its own entertainment. Doing otherwise would be pandering and also discriminating.
If the cast should reflect realistic human distributions, the bridge would probably consist entirely of Chinese and Muslims.
It's not fair to call Trek racist. Not fair at all. This show has done more to promote diversity in the popular culture than any show in TV history which I can recall. It may not be perfect, but it certainly isn't the opposite of what it stands for.
As I've said before, I would not begrudge anyone from any race for wishing to be represented by a main character in a Trek series. But don't expect the show to be anti-caucasian, unless pandering would satisfy you.