Difficulty of old raids

I already made this post here: http://eu.battle.net/wow/en/forum/topic/7669156855 but it didn't get any attention, and I would like to hear your opinion about this.

I'm not sure that has this been suggested before but it would be great if something would be done to the older raids (and maybe even Cataclysm raids) difficulty.

I myself started playing at WoWtlk and didn't really got to raiding untill Cataclysm came out and because of that I pretty much missed a whole lot of things from the lore and I haven't really experienced that much of raiding. So..my suggestion is that when you enter for an example Black Temple (which is lvl 70 raid) and you are lvl 90 you get to choose if you want to do that raid "configured" to your own level, so it will be just as hard that it was back in Burning Crusade for player at lvl 70.