Well avi, I agree it's a good idea, but the general activity of WA/TuS isn't enough.
For example, I am strongest at BnG/Hysteria/Roper, and not so strong at the other 5, I never practise them, I only play them when it's 2v2 clanner.
There are many many players like me who are good in 2/3 schemes, and not the rest.
People can only play this game in the spare time they have from School/College/Uni/Work/Women/etc...
I think it's very unfair to allow this option based on some people have more time available to practise all the schemes than others.
Even if you said "Yeah well it's their responsibility to make sure they have time to practise all schemes", I still think it's unfair, in some countries it's harder to make good money for a living and so they may have to work longer hours, or their parents are rich and they don't really have to work, or they don't care about school and spend time on WA instead of doing homework.
I think it's safe to say making a living/working towards a stable future deserves a higher priority than playing a game.
Also, why should someone be able to ban a scheme and perhaps even force them to choose a scheme where they can't even win as much points?
Think about it, for example in TuS singles it's me vs barman, I am the only person he can win good points in BnG, so to improve his overall rating he could pick this as also he's one of the few people capable of beating me, but ooooooh, wait, what's this, FU BARMAN, I BAN BNG MWUahuAHUa ! Now as he has WAY more points than me for other schemes, I just need to win 1 scheme to come out on top here...
It's a kind-hearted idea, but I don't think it's suitable for TuS.