I intend to sidestep the question of whether getting mounts at level 30 with upcoming patch 2.4.3 falls on the Dark Side or the Light Side of the Force. For now, I'm going to muse briefly on what impact this change will have on gameplay.
- Speed of leveling: Obviously leveling will be faster with a mount between levels 30 - 40. I doubt it will be 60% faster, though.
- Questing: Going through Thousand Needles, Alterac Mountains, Desolace, Arathi Highlands, and Stranglethorn Vale will be much easier. I remember Desolace, in particular, being one long drag after another.
- Economy: Lower levels will probably do more farming professions in order to raise the necessary gold for training and a mount sooner. This influx should drive down the cost of materials a bit in the short term. Also, given the low amount of silver rewarded at low levels, expect to see even more begging.
- Guild recruitment: Players who normally would've waited to join a guild before Level 40 (to help with mount costs) will want to join earlier now. On the other hand, guilds may have a tougher time keeping those players through endgame since there will be a longer span between getting the normal mount and getting the epic one at Level 60.
- Incentive to advance: The game has built-in "carrots" to encourage people to keep leveling. You already get them at levels 20, 30, 40, 60, and 70. You'll still have reason to level to 40 (new armor, etc.), but now the drive to 30 becomes more insistent. However, the down side is that there's a long drought between 30 and 60 to wait for the epic mount.
- General PvP: Racial attributes like travel form, aspect of the cheetah, ___ become less of a factor in terms of escaping or hunting down other players.
- Battlegrounds: Much has been written about how earlier mounts will even further tilt the balance toward twinks in the battlegrounds. But let's be honest here, twinks are already overpowered in battlegrounds (being the biggest reason I don't play in them very often) and, after the economy settles down, that advantage will be minimal.