If there was mass available to add something to the sky crane, you'd be better off putting that thing on the rover, since the rover has the plutonium power pack.
I do feel a bit sorry for the crane as well though :)
This is what I was thinking. That sky crane has to be as barebones as can possibly be made. Every single bit of mass on it is something that could be better used elseware.
Tradeoff of course is if you skimp on the mass too much you'll get an unreliable sky crane and the whole thing is a dud.
Sky crane will be used for seismic measurements with another vehicle picking up the waves from it slamming into mars firma on the other side of the planet so some use of it at least!
I do feel a bit sorry for the crane as well though :)