The problem is that learning to think this way in general makes you habitually write things like x >> 8 instead of x / 256, which makes your code hard to read for no benefit if you're using a compiler that was written sometime in, oh, the past 20 years.

EDIT: sometimes x >> 8 is clearer, if you're actually dealing with packing bits into words, but I've just recently seen it done when the code really "meant" division.