One of them a few years back for a small project (roughly $3M development) was all kept in wiki format.

I agree with 99% of what you said. When an investor has provided $3m, they want to see the big GDD to know they will get a good return on their investment.

For Indies, lone wolves, and newbies starting out it is my personal opinion that a large GDD can be a deterrent that puts people off their big idea. I guess sometimes this is good because it teaches them that their goals are too lofty and to scale back a lot.

Other times it could frighten away someone from gamedev.

Definitely, for those wanting to get a taste of real world software development, do it your way. :)

"I have a game idea!"

Your idea sounds a bit like Second Life, perhaps with a few more typical "game" type features initially available -- you might get some ideas from what they've done.

Or Landmark. Which not surprisingly, is created by SoE who have lots of combined MMO experience already.

Negazina, I think you are pretty close to figuring out what your limitations on the design are. Setting up and maintaining the infrastructure to support a MMO with thousands of players has a very different set of problems to solve outside the domain of gameplay design and programming.