|The good old days|
Coming back to WoW is hard. Logging into old mains means coming back to bags full of items which you don't remember what they're for, abilities which might not (or definitely will not, depending on how long you've been away) work the same way they used to, you're behind on content, and you're definitely rusty, potentially having lost some of the muscle memory of how to play your class. My level 90 Priest has all these things in her bags and all these abilities I don't remember how to use and there are all these dungeons and scenarios I have no idea how to run. I'm worried that if I tried to run anything I'd be terrible and everybody would hate me. My level 86 Druid is primarily Guardian but the class/spec changed so much in Mists that I don't even know how to play him anymore.
WoW isn't alone in this issue. Any game-as-a-service that updates its content and systems is going to have this problem with returning players having trouble catching up. They've certainly worked on making coming back into the game easier for players over the years. Simplifying the talent and abilities systems have done wonders for that. But the baggage of items, quests, and being behind on content is a harder problem to solve. I could just vendor the items but that's sub-optimal in terms of profitability and my brain tells me, "No! Don't do it!"
The game is complicated now. It may be (debatably) easier now than it was in Vanilla but it's far more complicated. With daily quests, normal and heroic scenarios, normal and heroic dungeons, normal and heroic raids, justice and valor points, LFR, and reputations (some of which are gated) PVE is incredibly more complicated than it has ever been. PVP has evolved significantly from what it was in Vanilla as well.
So I've been eschewing my high-level characters since coming back to WoW and have been leveling some classes I haven't leveled to the level-cap before. I've got a Draenei Prot Warrior (yet ANOTHER attempt at doing so), a Human Affliction Warlock, and a Night Elf Assassination Rogue. None of them are level 30 or above yet but I've really been enjoying the experience. Starting a new character lets me forget about all the things that have changed that keep me from playing the characters that are at higher levels. It lets me forget that things used to be different and that I don't know how the game works anymore.
I haven't really leveled a pure DPS class before, and leveling these has so far been really fun. I hope that this will help me get back into the game and really get back into endgame activities, which I haven't done since early Cataclysm. If you're having trouble getting into WoW lately, or haven't played in a long time, I highly recommend rolling a new character, it's very freeing and I haven't lapsed as quickly as I have in the past. I'm really looking forward to what these new characters will bring me.