I agree with Laterus about preserving the original intention of the author. To dumb things down so that they´re more palatable is patronising to the target audience and has the long-term effect of making people dumber.
The philosopher´s stone is a well known concept that´s been around for hundreds of years. The term carries with it lots of connotations, including:-
(i) the search for an ultimate truth
(ii) the confusion that once existed between science and magic
(iii) the pursuit of wealth
(iv) the futility of searching for something that doesn´t exist (or more precisely, how looking for one thing leads you to discover something else instead)
I imagine that JKR expected readers to pick up on some of those connotations, just as Colin Wilson did when he chose the title for this under-rated novel (which is, btw, a page-turning classic about the power of the human mind, highly recommended):-
If JK´s original title had been left unchanged, it might´ve prompted some American children to learn more about the history of science and the history of Western culture. As it is, they have been denied that particular route of enquiry and JKR´s title has been robbed of a certain resonance. And for what ? Some venial marketing decision.