There was some discussion on this here: https://www.warlight.net/Forum/90255-force-join-games?Offset=0
I have to say though, after playing with this for awhile, the auto join is actually very nice. Honestly I think it's a change for the better, and speeds up tournaments a lot. Imagine for example a 32 player tournament (3 day boot), one player always wait for the force join. Lets say he wins every game, so it becomes 4 games total. Skipping lobby now makes this tournament finish (3*4) 12 days quicker, assuming he was the slowest player. Keep in mind, that with more players, DE, longer boot etc. it saves much more time.
RT ladder (and tournaments) is the only place where I'd find this debateable, though overall the time saved outweighs the downsides; After all you should be ready to play them when you join, and if not you can just leave. Tournaments you cannot leave ofc, but this update will shorten down the time you'e to wait for other games.