As long as SE doesn't introduce a penalty for disconnected players who do not reconnect, the free pass to leave is already there anyway. All it takes is having a player hit alt+F4 or disconnect the LAN connection. To the rest of the party it will merely appear as a DC, they'll vote kick the person out and wait for a new player. Whilst the person who wanted out can log back in roughly 5 minutes later and requeue up if desired.

So might as well introduce a free pass to leave. It's not like it'd make much of a difference.