I understand... but sometimes you get to wait a lot to join a group... so you, forget and go away (and to be honest it has happened to me, when I get back I am in a group and I swear I feel bad about them for waiting on me... ) ... or you start doing something else... and you are getting quest items, perhaps the last mob you need... you just need 2 more secs... and you are auto joined, and probably changed from server...
Wouldn't be better, if at least ppl would have up to 30 secs to hit accept or just get rejected in the group? It would make things better, imo. And, waiting up to 30secs on someone to see if joins or not, I don't think would make the raid leader subject to anything... is just giving the ability to auto accept, or to auto reject if 30 secs have passed and you have not clicked on "accept".
And to be honest... the other day I was doing a tempest keep kael'thas for the mount, I got the auto accept, and since I was there, I got kicked from group, which made me, to get kicked from the instance and miss the 5 secs I was about to finalize the boss, had to restart it. Having the ability for those 30 secs, I would have declined and re apply after finishing the invite for the group.
Again, I understand the "raid leader being subject of... " but, if you get in a group (and you were in queue with 10 more) and somebody else invited you to another group (that you clearly auto reject) but you know that guy is from the group you would like better, you just need to drop group, re apply and you get instant invite again, so that "suffering" for the raid leader, s/he gets it anyways.