I'm not talking Matchmaking, but I do think we need that too.
There is a LOT of empty space in the tower. Even when its 'full' of guardians its very very empty.
My suggestion is to make a sign board or 'job postings' in all sorts of different areas (Does FWC really need all that space in the bar?) Where like minded individuals can go, and meet and wait. When another like minded individual heads to this area, they can wave, point and dance, showing interest and agreement that they indeed want to do this Strike, Crucible, Raid or whatever. At this point they can send their invites without likely pissing off other players (though people may still spam invites).
Have a spot where people can gather for:
Daily Heroic
Weekly Heroic
Nightfall
VoG Raid
Crucible
Iron Banner
Queens
etc...
you get the idea I hope.
That door where the Queens Emissary was parked.. that freaking HUGE area.. empty.. could entirely encompass this idea. A NPC, or 'indicator', or 'board is put up.. people come. They meet and they game.
Barely any effort needed to implement. Its still mainly Player initiated, just now we know who is thinking about doing what, and we don't even need text or voice chat to realize our dreams are the same.