Er... some manufacturers *have* figured out how to build a machine that doesn't run quite so hot, despite using the same processors that Apple uses. I think the secret has to do with designing and building the enclosure to allow proper ventilation and cooling, rather to simply be as "OMG shiny!!11!" as possible...
To all the folks who wanted Apple to see greater popularity: you got your wish. This is what happens when you go after the cheapest segments of the market.