I agree that most of these bands mentioned aren't what you'd call old school. Old school metal is traditional heavy metal, '80s thrash/death and hard rock/glam, etc...
The bands of today that would be considered "old school" would be bands such as Hammerfall, Edguy, Dream Evil, Dungeon, Iced Earth, Jackyl, Talon, Pink Cream 69, etc etc etc.
Not bands like Disturbed, SOAD, etc as they pretty much define the new school of heavy rock. All music borrows elements from older stuff, that's just how music evolves, but it doesn't make them old school. Old school bands are ones who play an old school style, not a new style with a few elements of their influences.
Even melodic death metal bands I wouldn't call old school as its a new style that has evolved in the last 5 or so years. It's got alot more old school metal elements than Disturbed etc though. To metalheads, I don't think melodic death bands are generally considered old school as its a new thing and much more original than say power and speed metal is. But to the MTV fan, bands like Arch Enemy would be considered old school because they don't rap and jump around with dreadlocks to mosh grooves.