I was reading a (rather old) review of Castlevania: Harmony of Despair. There a very telling paragraph that comments on the porcess players go through in the lobby to play online:
"For a multiplayer-focussed game, the lobby system is a bit of a mess. There's no way of searching for games by what level is being played - or difficulty for that matter - and it's largely due to the fact that the game makes you lock a party in before you can even set up what you're going to do. This invariably leads to most online jaunts being one of two thing - getting booted out of games when everyone wants to play the last level on Hard and you're not there yet, or being on the other side and having to guide beginners through early stages again."
Assuming this is true, this is a real significant usability issue. The process for players to get online, and get playing should be as painless as possible - but they also need control over WHAT they're playing.
The only reason I can think of for the process to be set like this is because the designers were unsure of the numbers of players who would be playing online, and so thought it best just to put everyone online in 1 group.
The paragraph says it all really. This is the current process:
Join group -> Select difficulty and level -> Play (or drop out if not to player's liking/can't play)
An alternative process could be:
Select difficulty -> Join group -> Group vote on level -> Play
The initial selection (difficulty) is essentially a filter, so players looking to play at the same level filter out the other players. Once the group is formed, there's no point selecting a level that not all the players can play (so they group must split immediately), so only levels available to all the players
should be offered.
Ideally the initial filter would also include level choices, but if there were concerns around the numbers of players this could be removed/left out to ensure sufficient numbers of players could find each other.