Then again, potential developers know it's going to be a pretty much guaranteed seller. I'm not sure if developers get paid more if the game sells better, or if they get a fixed sum up front regardless of how well the game sells.
If it's the former, then even with Lucasarts' "pushy" style, I'm sure a lot of developers would take on the project if it would get their company both revenue and notice.
I think of it this way: Lucasarts is like working for a big company. Sure they are demanding and sometimes unrealistic with their schedules, but they pay you a six figure salary (just an example, no Obs developers correcting me on this figure). On the other hand, you can work for a less demanding "boss" like, say, McDonalds and make $7.50 an hour with no stress or headaches. I'm sure a lot of people would be willing to take the stress and headaches with a big salary over a carefree $15 grand per year.