In a post on the official forums, I recently read someone saying that the player base is full of people who came from mobile games and mobas and Blizzard changed WoW to suit them as a result. I would argue that this is backward from the reality. In my view of the events as they unfolded, MMO developers saw the booming mobile market and realized that the developers of mobile games were making tons of money for minimal work. They were doing so by creating repeatable daily content rather than a vast array of non-repeatable content and then compelling people to keep playing in various ways while offering conveniences (and more) via cash shops and microtransactions. MMO developers saw this and, since money talks, they began changing their games to be more like the mobile business model. As a result, many old-school MMO players did not like these changes and began leaving the game. Simultaneously, many players who hadn't played MMOs in the past or were mobile gamers began playing WoW since it was similar to other things they enjoyed. Thus, the player base changed as a result of a shift in design philosophy, not the other way around.

I agree with you. WoW had to change to stay relevant, though. With the instant gratification games being popular and MMORPGs losing the spot as the #1 genre to play, I don't think a Vanilla WoW/TBC model in retail WoW would work as well as current retail WoW does. People want to feel like they grow stronger instantly, instead of waiting another week, in the hopes of getting loot. They want to not be gated out of content.

The difference between the casual and hardcore WoW retail raiders is bigger than ever. You got retail raiders putting in more hours and dedication than ever before, in any expansion or state of the game, meanwhile you got the casual playerbase having way more content to do than ever before, which keeps them in their respective places. The casual player is very unlikely to change into a hardcore raider, especially because the gap is so big.

Notice how the average player in about any game today, is usually way better than the average player back then. It's just in their blood to optimize and look up guides on how to be the most efficient.

I do think developers can force change a game and cater to a different audience, Blizzard did that with World of Warcraft. But the people playing games these days have absolutely also changed themselves. The newer generation is way more into the competitive aspects.