Fact:
-Hardcore MMO Raiders will consume content faster than it is possible to create.

Lets try this. SE makes a new Raid harder than Coil every 2 weeks.
Hardcore FC Raiders will create grueling raid timetables in order to be the first to clear each one before the next one is released.
Result? members of said FCs will become burned out on the game, or potentially cost these people their personal lives.

You can't make quality content without time.
Time is something MMO's have a lot of. People need to understand that and stop rushing through everything.

Personally, I'd much rather look forward to big updates with a lot of different things for people to do. Incredibly short tiny updates that only add things for the top 5% of players isn't exactly a good idea.
Even if you rotated the content coming out for raiders and normal people, the raiders would cry that the casuals are ruining it for them.

Imagine the stress on the Developer Team to make quality content in such short bursts.