I do feel that casual players should be able to get the Majority of the gear that anyone else can get, but I do also feel that there should be at least a few things in the game that only hardcore players can get.

Think about it in real life examples. This person goes to only highschool, this other person goes to highschool and goes to college and gets a degree in a field that he will be able to get a job in and live quite well off.
The second guy is going to have a much nicer car to drive to work in than the first guy, because of the time he put into it all. IT IS FAIR, regardless of how you look at it, if you take the jealousy and envy goggles off.

Again, I don't mind if the more casual players have good gear, but if I can fight an extra tough NM, or do a long dungeon/raid or anything like that, and get a special piece of gear that not everyone is entitled to.. well what do I need to explain about that?
It's awesome, something to wear with pride. If anything they could make the items tradeable so the more casual players have at least the option to buy them given the chance, but otherwise leave it to the hardcore players to earn them.

If there will be no purpose to the dungeons, or raids, or NM's, then they might as well not even exist at all.