I like this idea.
I don't like this idea.
I've got a different suggestion for this issue.
Fireteam formation is fine, leave it alone.
This idea won't work because...
In explore mode, what if assists and proximity to other players were used to automatically generate on-the-fly fire teams? Help somebody out in a fire fight or two, and stick together long enough, and you each get an automated join request. Wander off from them for long enough (or go to orbit) and the team automatically dissolves. I know with the XBL service you can set your "play style" (casual, family, hardcore) so you could provide an option in Destiny to only team you with people with matching play styles. (or only people with microphones) Not sure if PSN handles things in a similar way. In the beta, the social aspect just seemed under developed. Dancing and emotes are "social" in a trivial sort of way, but being able to quickly and intuitively play the FPS part of the game with other people would be a lot more interesting. Think about standard MMO mechanics...it's two or three fast clicks to start a team. With limited controller real estate on consoles, providing an automated option for teaming that takes place on the server-side and is mostly transparent to the player (aside from confirm/deny) would go a long way to making the experience more team oriented for people who don't have friends who play, or don't want to join clans.