Some class systems from the original game simply don’t have a modern equivalent. The class probably most affected by this is the hunter. The pet happiness and loyalty systems were removed a long time ago, as well as pet training and the ability to use both a ranged weapon and a melee weapon. In these cases, converting the old data to the new system wouldn’t work, simply because there is no new system to match. In this instance, we had to bring back the old code—and we did. Fortunately, the restoration went smoothly, though the reality of having to buy arrows or feed their pets again took a few people in our internal tests by surprise.
Who is Joana? Joana, (AKA Mancow, or FuriousPaul) speedran 1-60 vanilla WoW from 2005 - 2007. I have been server first to level 60 seven times in a row, along with winning Blizzard's "First to level 50" contest they held back in 2006. I also have the fastest time through original vanilla 1-60 WoW in 4 days 20 hours. I have produced a very useful 1-60 horde speed leveling guide along with a 1-60 speedrun video.
There’s the reason why some players used to call the game World of Roguecraft. Rogue was one of the most popular classes in classic WoW and there’s a good reason for it. During vanilla, Rogues topped DPS meters in raids and dungeons, but their main strength was world PvP. Rogues could stealth through enemies avoiding unwanted engagements with the opposing faction. Additionally, a huge variety of crowd control abilities and high burst damage made them the worst nightmare for the cloth-wearing classes. However, Rogues were in a bit of disadvantage regarding end-game gearing since most of their gear pieces were useful to other in-game classes as well.
For some weird reason Warlock used to be underrepresented in vanilla WoW. However, the least popular doesn’t mean that they were bad. Warlocks had amazing damage and some truly unique utility abilities allowing them to summon players or create Healthstones for the whole group. Similarly to Hunters, Warlocks were amazing for solo players with the ability to summon various demons to help them.