To be honest it probably would hurt the LFG group. Right now all of us need to use a LFG site if we don't have the friends online. If it is an even 50/50 split between OMM and LFG that means that they would only have half of the options available to them.

having the option is never a bad thing

True, but put yourself in the other sides shoes. People are leaving Destiny every day. This means that there are fewer people using LFG sites. Bungie has already stated that year 1 gear will stay in year 1. This removes another chunk of people from LFG sites, because they don't want to run old content for no reward. See what I'm getting at here? If OMM was added for all activities how many people would be left in LFG? More options for us means fewer options for them.

I can see that point of view as I too do use LFG Bungie should just add a clan system with optional matchmaking or LFG system into the game if LFG was in the game from the start then I would consider this game a social game success, as it is now it is a anti-social success