>>96410864
Tau are kino additions to the setting because they're just that diverse, and are a breath of rational noblebright/nobledark scifi in an absurd, grimdark universe.

They're great because they genuinely try to do the right thing, only really falling short due to lack of awareness of alien psychology/geography (thinking the Trad Tau'va would work on humans or orks without any alterations, or having no clue what the fuck a 'Slaanesh' is), and being too optimistic in trying to do the right thing (trying to spread the greater good to Orks and Tyranids). But that's their big flaw, naivety.

By including them as a minor part in the setting, you make it so much better.
>You introduce a xenos version of the Guard, solving irrational problems with rational (and now 'modern') military means.
>You make a contrast showing just how bad most humans are next to them, given their conduct. (I swear, everyone goes on about humans in the Tau empire taking chems or getting vasectomy's to dull their hormones to better mesh in their new life, and forget the average Imperial world does the exact same thing, except the chemicals are carcinogenic).
>You show that, for all the Imperial Propaganda, that a functional Utopia is possible, even with external pressure.
>And then in the same breath, that humans aren't suited for Utopia's by our basic natures.
>And when you reflect all that in-setting, you introduce ANOTHER threat to the Imperium. That being an informational threat. Seeing how good they have it, and how decently they can act to each other, would tempt even an Inquisitor steeled against chaos or imperial politics.

Sadly like everything else in the setting, they've been flanderized a good deal in recent years into mecha space commies that do 'clearly evil'.tm activities for no reason save to make it clear you're meant to root for the humans/astartes.