The Tau were introduced into the game at the time when WH40K was first being introduced to the Asian market. It was felt that an oriental feel to the race might make it sell better.
http://www.lounge.belloflostsouls.net/showthread.php?52423-The-Blood-Pact-Chaos-Homebrew-Supplement&p=472214&viewfull=1#post472214
It has tremendous merit for study, don't listen to the reductionist camp, I'm sure Joseph Campbell would have had plenty to say about Lord of The Rings and Dune if he'd bothered. And don't worry about it turning into a chore. If you love it, it'll sustain your hours of study, and you'll look at it in a new way.
Innocence Proves Nothing
Me, I think the Tau are based on British colonialism, particularly the Indian Raj. The Tau are the British - all-powerful, plenty of tech, condescending. Everyone else - Kroot, Gue'vesa, the insect guys - are the natives they variously conquered or insinuated their way into controlling. (Notice that the insects were, ahem, "gifted" with helmets that seem to make them all-fired-up about the Tau?) A colonial army back in the day was largely native sepoys, led by members of the white culture present - and after rebellions such as the Great Mutiny, the sepoys were deliberately prevented from having up-to-date equipment, so they could be crushed again if necessary.
It's certainly not "taking it too far." The question is, can you actually get a good dissertation out of it? There are a lot more things that are fruitful to study than there are that will get you a good dissertation in the realm within which you're supposed to be producing a good dissertation. If your job is to produce a dissertation about sculpture it probably doesn't matter how much you love Jane Austen, or how worthy of study she and her works may be.
Similarly, given that you're a film student, I'd ask: what would you use as source material for your dissertation? Regardless of how worthy of study 40K as a whole may be, can you identify specific works that are appropriate to a film dissertation that you feel are worthy of having a dissertation written about them?