I mean, it depends on which version of the lore you take. Their culture is repressive, with less social mobility than the Imperium or the Eldar, thanks to the caste system. The Ethereal Caste are doing something hinky and mind-controlling to everyone else. The one General who said "hey maybe we should learn how to fight up close occasionally" was banished. There's a lot of darkness there, and the disconnect between the Tau and the Warp makes those "little" things more notable.
Imagine if the Tau get eaten by the Tyranids or a Genestealer Cult. They might not cast the Shadow in the Warp, removing the one form of warning of their presence.