People will start to sell runs earlier, they will also sell more runs. Right now a group can sell 1 run a week, with this change the number of runs sold would skyrocket. Ah what happy times those gilsellers would have.
While being able to help FC-member completing content they have a problem with, you will end up doing them a disservice. They will not learn their class if they get carried, there will be no reason for them to improve since the boss will go down anyway and they will get their loot without having to do anything.

Coil drops the best gear in the game, the lockout is there for a reason. SE does not want everyone to have access to the best gear from day 1, week 1 or even month 1. For easy loot you have CT, that is the purpose of CT.