As we all know we have 4 difficulties of raids. LFR, Normal, Heroic and Mythic.
In something like Classic, there is only 1 difficulty. 1 difficulty makes beating a boss, all have the exact same experience, all have the exact same loot dropping, all have the exact same feel of guild progression once it dies.
In Retail... You do a raid in LFR. Then it's not really a challenge, nor do you get any good gear from it. OK. Then you maybe find a guild and they do Normal. Still. The gear is just, meh, compared to M+. You already beat all the bosses on LFR, so it's not that cool to see a boss die. Repeat at Heroic difficulty. 3rd time I kill him? Eh ok. Same loot, just scaled to better ilvl? Eh ok. Mythic raiding. We already beat the same bosses on 3 different difficulties with the only benefit being scaled up gear. Why would we bother pushing into mythic? ...
Why not go back to the TBC model. Some raids (early raids) are easy. Some raids are small 10 man raids. Some raids are 25 man raids. Some 25 man raids are easy. Some 25 man raids are hard. Everyone has something to do.
I think the "Oh shit I beat Illidan!" feeling is completely gone in Retail due to the 4 difficulties. When you tell your friend you killed a boss, his first response should be "damn thats so cool!", not "what difficulty m8?"...
This multiple difficulty tactic from Blizzard might work on paper, more % of the playerbase see all raids than ever, probably... but at what cost? At the cost of anyone caring about getting gear enough to see a cool raid boss.
"Seeing that raid", "beating that boss" and "getting that loot" used to be the main motivator to rise up to be more hardcore. Not just "if u wanna beat same boss for the same gear scaled, go ahead m8. Maybe we throw in some mount for it too lol"...
Raids don't even have to be hard for people to enjoy them. Just look at classic and MC. It's a million times more fun to kill Ragnaros in Classic compared to killing Azhara Mythic in Retail, even if she is much MUCH harder. Harder does not mean better for the game.