This inspired me to read through the Tau Fluff. And It got me thinking. Are the Tau REALLY a major threat? Or are they just something for everybody to kick the hell out of? I mean they excell at nothing their philosophy is annoying and they just don't seem to have any real understanding of how the Universe operates. Their Etherials are an Interesting idea but any Psyker with a middling competance is going to shred them. I've read precisely one novel with the Tau in it and they got beaten to a pulp.
You can't really judge a race's fluff worth by how well they perform in the table top. Right now, the tau aren't big players in the galaxy. They're technologically advanced and steely enough to pose a threat to the Imperium, and since they haven't been wiped off the face of the galaxy yet we can assume they're too powerful to be killed off by anything but a long, grueling war. Really, I think the tau have a couple of advantages that make them stand out and give them a chance to survive in the hostile universe:
1. They're extremely resistant to chaos corruption.
2. They're willing to assimilate other races into their fold, and have done so with great success.
3. They're one of the, if not the only, race still in the galaxy who has both the means and the motivation to develop new technology.
Another thing i've noticed is that many many Veteran players hate them. I do myself their hippy trippy greater good stuff gets my hackles up.
Hippy trippy? I see the greater good as basically space communism/socialism. And to my understanding, most veteran players hate all new races brought into their game, like the necron. They seem to want to justify it with their sleek look, giant mechs, and reliance on plasma weaponry. I've heard "you got your anime in my Warhammer!" is a common addage by tau detractors.