I have often felt that the aliens of 40k that share human links (Look pretty much human e.g. Don't have 8 legs or bristly bodies - Obvious exception of Vespids and Kroots etc), almost similar goals (Eradication Chaos above all) and try to live peacefully amongst the havoc that surrounds them pretty much the same way the Imperium deals with on a day to day basis deserve to have more coverage in novelisation.
Eldar have had some coverage thanks to C.S Goto and Gav Thorpe
Fire Warrior is the only full novel featuring the Tau that i am aware of. That was a novel based off of the computer game of the same title.
Are there any shorts featuring Tau?
I know they don't seem to be too exciting in comparison to the IoM and Space Marines however they are the youngest ever growing empire that should have its origins, beliefs and military portrayed better.
What are your views?