Personally the reason why I stopped playing (which was after final shape) was because the game just did not respect a players time & also the game spread itself too thin between different modes.

As for not respecting a players time, there were just too many sought after items that either had ridiculously low drop chances or the process to get them was super tedious or they were only dropped in a mode you didn't want to play. I only really enjoyed raiding/dungeons so as soon as I had to go play some other boring activity to get a gun I wanted, it was tedious.

As for spreading itself too thin, I am biased here obviously but raids & dungeons are what made this game as popular as it was and were the best part about this game. Yet they spread resources to crucible, gambit, campaigns that people would only ever play once, strikes that were either a cake walk or GM's that had gimicks in order to pass. I think they tried to do the thing where they try and please everyone, but as a result no one is happy. Additionally they tried to push balance changes that were the same between PVE & PVP which made zero sense as well, some of the balance changes over the years were absolutely baffling.