The point of the game is to have fun, and if someone wants to surrender then they are obviously not having fun. If you are having fun playing a losing match, then you can have just as much fun when you start your next losing match. Meanwhile other people who have a limited time to play would much rather go on to something a bit more even.
Removing the ability to surrender is stupid. You can force everyone to continue playing, but you cannot force everyone to continue playing well. The second everyone gives up, the match is over. End of story. Just because it's physically possible to win a losing match, does not mean it's possible with the players that you have or the mindset that they are in. If someone honestly thinks the match is hopeless, they are not going to play well at all. I have had winning games thrown by one player because he thought it was hopeless from the beginning (he had no kills and only a couple assists). It's not that he did it on purpose, it's that he wanted the match to end, so he subconsciously played badly.
If anything they should increase the ability to surrender. It shouldn't take 4 votes to end the match, 3 should suffice. If someone disconnected before the 20 minute mark, then you should be able to surrender sooner.
The only time I advocate removal of the surrender option is in ranked matches.