I can sort of answer this by looking at guild wars 2, a game I was playing for a few months recently in my down time.
The answer basically comes down to while they do something right, they don’t do everything right and the stuff they don’t do right can drastically take away from the game.
For example, their pvp gearing is super awesome, starting at lvl 10 you can warp to the pvp area and choose your stats and abilities and can have the same power level as veterans of the game. This is super awesome!
The downsides are they don’t have arena type game play and it’s basically alterac valley every game. I hate objective based pvp and only like arena.
Another problem is the gameplay isn’t exactly my favorite type for pvp. So basically, many games get something right but screw up in other parts which kills the game.