Do you miss the feeling of one of the rewards of your initial progression through a challenging raid being the simple ability to see more stuff?
At the end of the day this is a minor complaint and I do still enjoy progressing through Heroic for a bit and then onto Mythic but I sorely miss when you couldn't blast past and see the entire raid in lower difficulties. A sense of progression seems lost, to me, when you can clear normal in a night and you've seen it all, leaving only pure mechanics left for hc and mythic and no sense of 'we're working on this challenging raid to get to the end and to see it all'.
Simply put getting to G'huun and seeing the entire raid on the lower difficulties just can't compare with working your way through Kara, for example. In a way it's like completing a single player game on easy mode and then going back to play on the normal mode just for the challenge. Surely most would agree it's better to just play the game for the first time on the normal mode because it means more to progress through when it's hard.
LFR and Normal has been around for ages now so I'm aware of the reasons why they do exist but while I don't think Normal should be removed it does takes away that sense of unlocking a new area because of your efforts as a guild on the 'real' difficulties.
Update
I'm not saying that raiding should only be for the 1% again.
Heroic raids, for the purposes of this thread, is the REAL raiding for the vast majority of people. But it's ridiculous to expect everyone to gimp themselves by saying, 'well don't go into normal' when Blizzard gives you that choice.
The point is that most people want gear and so they'll go do LFR and Normal. The downside of that, the tradeoff of having everyone blast through the content on afk difficulty, (I'm NOT saying that only Mythic raiders should be able to see content) is that when they come to heroic they've already seen the entire raid. G'huun isn't as special because you've killed him on the lesser difficulty.