The only reason the lockout system is the way it is today is to promote static groups. The problem is that forming a static group is a job that requires a ton of work... which isn't all that fun.

Step 1: Advertise, advertise, advertise...
Step 2: Weed out any candidates who aren't fit for the runs.
Step 3: Repeat steps 1 and 2 until group is created.
Step 4: Base plan for progression on the ability and schedules of the current players. Be prepared for disappointment, because its always slower than anyone initially expected.
Step 5: Replace any members who fail to show up on time repeatedly...

Steps keep going on and on. You essentially become a boss and have to make painful decisions on who stays and who doesn't. The process forces the raid leader to throw a chunk of his humanity out the window because he has to be an asshole to a lot of people to make the static work.

Frankly, after ten years of it, I think I'm done. I don't want to play a game where I have to do that to people again.