You cant use the points though. Every tennis player who ever lived would win 1 slam instead of 2 Masters although the points are the same. I also think most would win 3 slams instead of 15 Masters.1 slam is impressive, but it makes them seem like a 1 slam wonder. Sure, history may remember them as someone, but someone who wins 5 consecutive Masters 1000s would be listed on the Wikipedia page for ATP Masters 1000 as approaching the record for most Masters in a single season. I can see merit to taking either. (Particularly prize money)
If you compare Wawrinka and Murray, i place Murray miles ahead of Wawa although they have the same slam-number. Its because of the combination of Masters titles and slam-finals. But I dont think that Masters titles will ever even out the number of slams. If one player has 15 slams and 2 Masters, he will always be ranked higher than a player with 13 slams and 10 Masters.
Thats just the way it is.