Because it may make you slightly slower for a week, but it makes you faster for the rest of your life.
Depending on how much time you think you'll spend in Vim for the rest of your life, that tradeoff may be very smart indeed.
Doing what seems easiest or most "natural" at first may not always be the best user interface in the long run.
The only people that would benefit are people who have not yet learned hjkl, and those people have no influence. What are you expecting to be done, Vim wildly breaks standards, pisses off existing users, and changes the default key layout? Never going to happen, never should happen. First off, because it will piss off existing users for no reason whatsoever, and secondly because nobody in a position to make that call would make that call. Thankfully.
Distribute Vim yourself with these changes; see how far you get.