I don't disagree that is what they are 'saying'. I'm merely saying that if they really wanted to separate them they would have them share a lockout and you could do A (story time) or B (progression time). Perhaps a better option is to just remove the loot, lockout, and further reduce the difficulty of story time so that people who want to expericent the story can do that.
I remember them well and I think the rumblings of "I can't do naxx?" were very minimal. It was understood that Naxx was a tough place to be and 40 people geared and attuned people were hard to find. I think Blizz said 7% of people saw it the first time around which is why the content was recycled.
I think that the casuals would then side with my above idea and i think that should satisfy both them and the 'hardcore' that are left in the game. Furthermore I think that following the 'story time' model, TFB (as well as EC) should be accessable on the same difficulty level as EV/KP in that it requires only Tionese to complete and drops Columi. I mean if we are going to say these people are just here for the 'story' then why are we gating their content based on gear anyway?