This is just an idea, And no i wasn't around in BC to see Attuning for things like BT and old Nax.
When a new 25/10 raid is released instead of the 25 being able to be instantlly entered all party members should have to complete the 10 man version in order to enter the 25 man dungeon. This would elliminate people easy modeing 10 mans using armour and gear from the 25 man at the begining.