They've never said that the exotic buff would be coming by a specific date, they owe you nothing.
Honestly they rush out a balance thing (autorifles, pocket infinity etc)...people complain. They take their time and...people still complain. Bungie should just do whatever they want because the vocal minority will be whining either way.
No people complain because almost every change they have made bar bug fixes have been to move everything towards being either average or below average and they haven't added anything to the actual gameplay.
They released a game without a huge amount of content and hid that fact behind a grind system that forces you to redo everything hundreds of times to get / upgrade your gear. They have then spent the time since launch mucking around with a few weapons and fixing "exploits" that people have used to make the grind easier.
The only two gameplay additions they have done are "heres cruicible with a tiny modifier for your actual level" and "heres another faction to earn points with by doing the same stuff as you already do".
Its getting boring and its getting frustrating.