the game engine was created around 360 capability and parts of the old halo engine .called tiger. start of development of tiger in2008. to cross platform to ps too. in coming years next gen began to be announced in 2013. then they considered one and ps4 after the fact.
http://twvideo01.ubm-us.net/o1/vault/gdc2015/presentations/Butcher_DestinyEngine_GDC2015_final.pdf page 40
video presentation https://www.youtube.com/watch?v=UU92a5pKV6k
360 isnt holding anything back, because the current game engine was built for 360.
theory is adding the one and ps4 maxed out the capacity to run. this may be the reason old content diminish as the game moves forward.
most have or had a computer ,right?think of it like this.
your memory is maxed out but you really want this new game.
computer wont let you install .
what do you have to do in order to install the game?
increase the memory capacity or delete old games to make room.
i just thought was was an interesting bit of research .
got more facts/links and info please share!
[i](this is not a post about old gen vs new gen war. leave that somewhere else)[/i]