They still die very quickly.... I've never ever seen a unit of kroot fighting their way thru a unit. MY BATTLE SUITS KILLS MORE IN HAND TO HAND!!!
There's nothin wrong with an all tau army. I'm all for it. But you shouldn't bash the kroot like that.
They can definately hold there own. Ever see a squad of kroot in a forest? (if you haven't, you should play with forest more!). Shoot 12" through forest, no difficult terrain checks, and +1 cover save.
As a dark eldar player, I had a very hard time taking care of ONE squad of kroot campin out in the forest with a team of crisis suits.
Throw in a krootox and sit still with rapid fire and crisis suit fire support, assault to finish off the squad with a shaper and krootox dealin out the hits.
Kroot rifles are also very impressive.