Terrible idea Learn to not horde items and not be lazy to go into your menu and dismantle items the responsible way. If the loading time takes too long then get a faster SSD
I guess it was a terrible idea in D1 when green engrams auto dismantled too, huh?
Green and blue are slightly different. Green becomes absolutely useless after a certain level, blue can "kinda" still be relevant. But I agree with OP and you that you should be able to choose if you want to auto-dismantle a certain color engram.