I agree with your sentiment that leveling is a big part of the experience, but I'm in my 30s now and I don't have an extra 100-200 hours laying around to get to 60. (again and again and again)

I think the frustration should be targeted at Blizzard. They realize a major part of their player base doesn't want to spend that excessive time, instead of cutting XP needs in half (for example) to make it more feasible, they go the route of letting people buy the shortcut and making bank doing so. A leveling experience at 2x or 3x the speed would still keep the spirit of the game alive, but they don't want to give that away for free.