Most of the veteran players I know that came back to the game quit for 1 reason that's never even mentioned here: Too many hotbar buttons and often ridiculous dps rotations. And these are people who were top 1% players in TBC or WOTLK, not random casuals.
Let me start by stating that one hard lesson to swallow in game design specifically, and in general life, is that there isn't just that one single reason why people quit. For most people, it is a combination of reasons--at least when it is not due to external forces like "I had to move and I don't have internet yet". They just voice that one primary reason on the front of their mind that made them vocalize the feeling they have when playing the game. But if that was the only problem and they had enjoyed the rest of the game, then they wouldn't have quit the game that easily.
This is also the reason why I don't find using player data and metrics, e.g. about the "absolute certain point where players dropped off from the retention graph" that
S
Secrets
managed that helpful. But I'll circle back to that topic, like you Americans like to say nowadays.
Nonetheless, they do have a point, but it isn't only the button bloat with each expansion and the more complex combat rotations. Of course, one-button combat rotations like frost mage, or the infamous TBC BM hunter macro went away with WotLK at the latest, but I think no one cries tears of sadness for them. Blizzard even pruned a lot of abilities post-Pandaria, and players bitched a lot the pruning went too far. Ability-wise, every talent spec has a page defining six core abilities, everything added on top should be situational, utility or fluff. Sometimes it also has a passive, for example, Atonement for disc priest.
Now for why your friends quit, I am going to assume what happened was this: The game evolved into quick, twitch-based, reactive combat. And not necessarily the good kind. Let me go over some points when comparing the core gameplay loop to its Classic iteration:
- Most specs have at least one proc. Blizzard of course flashes things on your screen for them, but that is maybe even counterproductive to a well-made WeakAura for spec-specific things.
- Players have to keep track of more things. One of the worst I think are Dot-cleave specs that need some sort of display for individual targets. Nameplates or extra addons alike.
- Fights finish quicker, at least for normal enemies, and there is no real downtime between fights. The game doesn't force you to take breaks anymore.
- The outworld on the other hand had its skill requirements reduced, sometimes bordering on insulting. It doesn't feel like a world where you defeat dangers and overcome odds. It starts to feel like a visual novel.
- However, in dungeons and on boss fights players have now to keep track of enemy abilities like casts, AoE's, or other special abilities. Blizzard sometimes does a shit job of conveying this visually to the player, at least in the default UI.
The last point is a pet peeve of mine. Blizzard doesn't have a "Consistent Visual Language" as FFXIV does, of what is happening, and what the expected reaction is from players. And I am not the only one who noticed that. This also came up when a WoW encounter designer
dissected an FFXIV raid encounter. You don't learn the game, you learn individual "dances". And these dances become more and more complex, some bordering on elaborate Bollywood routines. It's pretty telling when players explain boss mechanics with terms like "stack up like in that one other boss fight" and not "stack up because of a meteor."
To circle back to the player data analysis: Those
are pretty helpful, but only if you know how to analyze and interpret them in the context of the game. They can highlight some pain points and differences in design and player expectations. But they don't tell the whole picture. This is trying to funnel all the reasons into a "monocausal problem" bucket. Alleviating and/or outright removing them all may or may not make the game better. It even may lead to decreased player retention: The players that had quit at the first point could be quitting at a later point because it's just not their type of game. All while the players in your core target audience leave because the game has been stripped of all their expectations for that type of game.
This is what players call "the character" or the "soul" of a game. In the end, streamlining it long enough
makes anything into a round ball, and in the end essentially interchangeable with other, similarly polished games. It also explains precisely why Blizzard was dumbfounded by the success of WoW Classic: "We had a product but made it better and easier and more accessible over the years. All according to our data, management, and of course the consultants we paid a lot of money for. But now people still like the old, unpolished version! Why?" Maybe you shouldn't have listened to the consultants that tried to sell you something without knowing your domain-specific problems and challenges.
Sorry that I rambled on again. Maybe I should make videos of those and post them on a Youtube channel.