They had it right during Vanilla. They need to mix it with TBC.
Even though casual didn't get to "raid" in Vanilla, they actually raided. They raided their heart out. It was called "10 man dungeons" i.e: UBRS, Scholo, Strath Front, Strath Backdoor etc... thought I wish they called 10 man raid instead of dungeon.
The casual had their own raid, they had their own raiding gear to collect, T0, and especially tier 0.5... with upgrade and a few pieces of epic.
This was great! there was raiding for hardcore player and raiding for casual players.
Now they should go back to this system except, instead of 40, make 25 man the next step... so if casual who did 10 man raid liked it... they can work for 25 man.
IMO, 10 man got it pretty much right for both hardcore and casual ppl in Vanilla.
You had to use the community to do it and none of this rediculous "LFR" crap with epic that doesn't feel epic. Make right 10 man right and give its item a rank that make sense (rarity).