You refuse to see the point. You are making this argument from "this is the way it ought to be" and that scans fine for those of us who raid regularly. The "normal" or "story" mode is to entice the more casual player to participate in Ops. Having solid, across the board participation in Ops makes it easier to walk in and make an argument for more Ops at the high end...and more nightmare mode stuff.
Hard core raiders (read here, us) are outnumbered 9/1. That means the casual players will get what they want by dint of sheer numbers.
As for the rest of your post...people play MMO's for any number of reasons. E.g.
1. To escape their wretched, everyday lives.
2. To be a different person than yourself.
3. To play (at whatever level of difficulty) with friends.
A challenge is not necessarily the primary concern of the casual MMO player, and in fact, I suspect that "challenge" is way down on the list of reasons for casual players. That is why being a developer of an MMO is a thankless and unforgiving job at times, having to strike the balance between disparate groups of human beings, all that play for different reasons.
As for me? Bring it on, I want to learn hard fights and my role in them. Yes, challenge is one of my primary gaming reasons for raiding. But you act as if this is the way it should be for everyone...and that just isn't reasonable.
I just really see it as a very slippery slope.