Ah, I see.
You don't actually get the Tau at all, is what it is.
So, I really don't see how they're much different than the Dark Eldar in that respect. Yeah, they aren't a huge hulking menace to the galaxy like most every other faction. I disagree on a lot of those points. You may as well say any Space Marine chapter that isn't one of the big nine brings nothing to the table. Their guiding idea is actually more of a matter of manifest destiny. You know, what the Imperium had while it was on it's Great Crusade? They prefer to avoid a fight, sure, but that's mostly because they're literally the only faction that prefers to use diplomacy before death. Eldar manipulate, sure, but that's not really the same. They actually fight quite a lot. They do it when it's more desirable, and they go in prepared. They're boring because they aren't trying to murder everyone? Because I would think that the whole Damocles Crusade, and the tyranid invasions they've had to fend off, besides the WAAAGHs that have nearly killed them several times, oh and the mystery behind the Ethereals, and then there's all those various races they've assimilated that are fairly interesting, and in the more recent fluff they've gotten significantly darker, even if it's all shadows. Oh, nearly forgot the whole specialized castes thing and the hunting theme behind their tactics, not to mention the 'continually advancing technology' unlike every other faction but Tyranids (the out-adapting tyranids thing is still bullshit though, regardless of what factions I like). Or the reduced connection to the warp, the hints that maybe they might achieve real AI at some point and that might result in another iron men situation, or it might not because the Drones haven't gone crazy like that yet so there's that bit of what if, plus the suggestions that people bring up all the time about the issues they're gonna face and what they might have to change when they get bigger and absorb more human planets, and thus, psyker producing populations (personally I'm fairly sure they'll be okay after a few daemon-bumps, considering they've handled the Nicassar and Nagi just fine). Or the bit about their internal conflict, oh, but wait, that's obviously contrived and not interesting at all because reasons. Like, a lot of what you're saying, I'm just not getting. None of the problems? Problems of who? The Tyranids? The Necrons? All the problems those poor Chaos Daemons face on a daily basis? The Eldar face tough shit. The Imperium is the focus of the whole bloody setting and the whole point is how much pressure they're under and how many fronts they're fighting on. The Dark Eldar get fucked over every once in a while, even.
But really? You think they're neutral? Because they're supposed to be new and naive? See, no one's the good guy in 40k, you're right. But there are bad guys, and the Tau aren't one of them.
The Imperium has a million worlds to work with in which to produce interesting systems and stories. The Tau have maybe a hundred. I find that it manages to capture a lot of what grim dark is about; maintaining one's 'humanity' in the face of overwhelming odds, and suffering for it.
And really, that's actually a self-fulfilling prophecy. So are you saying the same is true of literally every other faction that doesn't have a story written from their perspective. I mean, when half GWs sales are Space Marines alone, not including all the other Imperium factions, are you trying to say that only the Space Marines are worth writing about? That it has nothing to do with who the setting is focused on or any bias on GW's part in terms of advertising? Really? They aren't in prep. They're in the very beginning of the Third Sphere Expansion. That's not a 'visible conflict' to you? Not enough worlds being Exterminatused?
So the themes of sacrificing oneself for a greater cause, orwellian society and propaganda machines, assimilation of other cultures, naivety, hope? These are all just ripped off, then? The stuff about believing other to be barbarians based on their cultural practices and colonial style imperialism, or the desire to win without having your men die? I mean, this is before the whole conflict between different cultures trying to work and live side by side, or between different Castes and the restrictions imposed by a society focused on the community rather than the individual. Are they timeless? Maybe not. But the Tau aren't timeless. They're new. Young. Are they interesting? I think so. I think they're worth exploring. Maybe you disagree.
And if you honestly think the Dark Eldar aren't supposed to contrast the normal Eldar, or that Chaos Marines and Space Marines aren't meant to contrast each other, well, I dunno what to say, man. I like most every faction in 40k because I can see what makes it interesting. There are some I like less, some I like more. If you only look at the surface, no, you're not gonna really see a faction as being even halfway interesting. On the surface, Imperium looks like it's just endless amounts of infighting, xenocide, witch hunts, red tape, and Exterminatus. Oh boy, mass murder. You have to look deeper. You seem to decide not to, with the Tau. You've made up your mind to dislike them and nothing anyone says will change your mind. That's fine, whatever.
Just don't be a dick about it. Because right now, what you're saying to me is: "the only reason you like them is because you think you're better than me/didn't want to be anyone else". It's basically you saying 'they suck and you suck for liking them'.
Seriously, nenjin. You don't have to fucking like the Tau. I'm not asking you to like them. I'm asking you not be a dick about it.