The holiday achievement What A Long, Strange Trip It's Been has been around since Wrath of the Lich King, before Master Riding was even a skill. The Violet Proto-Drake that was given as a reward from the meta was a 310% speed mount, something that was only offered through winning PvP seasons or through rare drops off extremely difficult end bosses in raids.
When the Master Riding skill was introduced in Cataclysm, players wondered what this meant for the future of the Violet Proto-Drake. After some deliberation, it was announced that the Violet Proto-Drake would automatically grant Master Riding skill. This was all well and good in Cataclysm, but with Mists and the account-wide mount system, it meant that anyone who had completed the holiday meta could get off scot-free on any and all alts as far as paying the costs of Master Riding went.
Apparently this didn't sit well, so the achievement has been adjusted. Whether or not it will remain adjusted by the time Mists goes live is up in the air. However, for those who have completed the achievement, the good news is that you'll be able to ride your Proto-Drake on any character you have. The bad news is, you'll still have to fork over the gold for extra speed on any alts that have not already learned the skill from the holiday meta in live.
It's open warfare between Alliance and Horde in Mists of Pandaria, World of Warcraft's next expansion. Jump into five new levels with new talents and class mechanics, try the new monk class, and create a pandaren character to ally with either Horde or Alliance. Look for expansion basics in our Mists FAQ, or dig into our spring press event coverage for more details!