It's a culture problem too. Just today, reading about OLPC:

Jim Gettys, responsible for the OLPC laptops' system software, has called for a re-education of programmers, saying that many applications use too much memory or even leak memory. "There seems to be a common fallacy among programmers that using memory is good: on current hardware it is often much faster to recompute values than to have to reference memory to get a precomputed value. A full cache miss can be hundreds of cycles, and hundreds of times the power use of an instruction that hits in the first level cache."[54]