: The only bad thing might be that as soon as someone sees it's join in
: progress, they might just back out automatically to avoid being unable to
: vote for a map or risk landing with people who just don't do teamwork well
: or whatever.

This is a major part of why I don't like their system and join-in-progress in general.

scenario:
you don't vote and people pick something you didn't want to play
the next time you vote and get outvoted for something you don't want
the next time what you want isn't even one of the options
the next time the server randomly decides you don't even get to pick, you'll get what you get and that's it

Do you know how frustrating that is?
The score thing would also be good in at least giving be some advance information. With join-in-progress, not only do I not get to pick what I play, I don't even know what I'm going to play until I'm actually in the game. Something like this would, or should, let me know that along with the score.