I can only speak for myself when concluding that leveling is essential to an MMORPG. No MMORPG has lived up to vanilla WoW for me, and the leveling is a big part of that. Classic delivered, but it was always a limited offering. If I had my way WoW would have built on top of Classic and delivered more of the same, instead of constantly re-inventing itself and make past content obsolete. Including bumping every raid tier to max level any time the level cap is increased, so everybody has to start from the beginning - attunements and all. Which would inevitably mean that getting to max level and to the latest raid tier would be an ever-increasingly daunting task. But that is kind of the point. An MMORPG should feel endless. That is important. That every player is engaging with "current" content is not. Modern WOW has become way too much of a story-telling vehicle - with phasing, cut-scenes and whatnot - to a point where it almost feels like a single-player RPG where you don't really feel the presence of other players in any meaningful way. Things like mob tagging and not being able to fly above content is a good thing, because it causes human interaction, good and bad, just like in real life - other people can be obstacles in your way, or they can be allies in a common struggle. The world must feel alive, populated by other people, and seamlessly connected and vast, it can't be like SWTOR where every planet feels like an instance rather than as part of a shared world. Things like the hassle of travel is a great way to make the world feel vast, flying makes it feel small and reduces interaction with players - whether those interactions makes you feel a positive or negative emotion they are essential.