Is there a particular reason to expect, the Stone having been introduced at all, that its powers would be changed? That seems somewhat less acceptable a change than simply leaving the Stone out altogether.
I'm guessing in MoR there should be no (actually working to significantly prolong life) philosopher's stone, as not using that more widely would be altogether too crazy.
I'm guessing that the working Philosopher's Stone does exist, but it is quite magically difficult to create, and many wizards have Dumbledore's attitude towards death. This would explain why more people do not use it. In canon, Flamel is noted as being historically significant for being one of the people to have successfully created the Philosopher's Stone. (Of course, in canon, it states that Dumbledore worked with Flamel on 'alchemy', presumably meaning the creation of the Stone. Does this conflict with Dumbledore's attitude towards death in MoR, or would Dumbledore have worked on the Stone without intention to use it for another reason?)
Dumbledore worked with Flamel on 'alchemy', presumably meaning the creation of the Stone
There's a lot more to alchemy than the Stone, which Flamel must have had for some centuries before Dumbledore's birth. So Flamel is a great alchemist, from which flow two consequences: Flamel made a Stone several centuries ago; more recently, Flamel worked with another talented alchemist, Dumbledore, probably on something else (since Flamel already had a Stone and Dumbledore wouldn't want one).
Update: This post has also been superseded - new comments belong in the latest thread.
The second thread has now also exceeded 500 comments, so after 42 chapters of MoR it's time for a new thread.
From the first thread: