I'd actually say it's the other way around, lack of mid-endgame content. Early game actually has a pretty good selection of content, but once you get to 110+ in the otherworld, you start to run out of things to do, and the level grind starts. That's why there usually seems to be a pretty good selection of <100 players throughout the game, but not many getting past that to go on to endgame. It also has to do with this being a mobile game, that requires huge amounts of time dedicated to progressing past midgame. I don't really have a problem with it (in theory) but a lot of people just starting the game may want something more casual....once it starts getting more hardcore, they move on to something more interesting then hours of lixing.
I don't think more bosses is the answer though. It's usually pretty hard to assemble a good bossing group at midgame levels. IMO the game should focus more on horizontal content that can be done solo...more like cooking and fishing. More bosses don't really count as horizontal content...all it does is bring in more loot choices for the top players on the server.
Point was that the players dont stick around long enough to get to endgame so while more endgame content would always be great, it wouldn't solve the early retention issue.
At a certain point it turns into a grinding lix and camp fest. Having to wait hours, if not days/weeks (extreme cases years) to have a chance to update quest gear (frozen armour, dl weapons) is kind of ridiculous. That's why more early to midgame content is needed.
By midgame I mean anything under 215.
Michael Artisan - Warrior, Blake Artisan - Rogue, Ren Artisan - Ranger, Gabriel Artisan - Mage, Yaray (until VR let's me add Artisan to the name) - Druid
Guardian Deity of Danu
Buying White Lanrik Pants on Danu!!!!