I suppose all interested developers already agreed we need to start from scratch. Over the years we have created multiple layers of CSS hacks, unused CSS, IE5.5 compatibility and who knows what else in our themes.

The theme cleanup steps are:
1/ remove old themes except "standard" which will be kept for now, other developers need something that kind of work during the great themes refactoring
2/ new "base" theme will be the parent of all new themes
3/ we will create brand new "newstandard" theme
4/ when "newstandard" is good enough we will delete old standard and rename newstandard to standard
5/ standardwhite|red|blue will be replaced by new "standardcolour" theme with colour related configuration options in admin interface
6/ other themes can be readded when updated