I think surely it depends who is asking. If ATC clear you direct to a point, then they remain responsible for terrain seperation. If you ask then it's a bit more hazy. I've been a big believer of "if you can see it you can avoid it" - I would have no issue asking for, and accepting a shortcut in day VMC below the MSA, but it would be silly to ask for it in IMC or at night when you can't see the obstacles.