I agree with Karajorma, sometimes there's a wide spread tendence to add a lot of new stuff to increase the *supposed* quality of the final product. I have experience wth this... :nervous:
Blaise Russel, Axem and Ransom Arceihn are all worth mentioning in a thread this kind, but I'm pretty sure things change when there's a team (and not a single person) working on a project. I am currently working alone on something which is expected to be ready in the next few days (speed FREDding, right!), and I haven't informed anyone about it. I realized, however, the difference between working alone and working for a team... the last time I worked solo on something was 3 or so years ago.
At this point, I believe teams somehow have to advertise: I can't imagine a team working secretly on something and then release it. I also believe the key to the success of many great campaigns is how they weren't developed by full teams of modders (one partial exception is Derelict, which was developed by Agatheron and Kellan) and did not attract a lot of attention until the release. When there are no great expectations, the opinion on a particular mod can only improve... things change, however, when it comes to waited and advertisted projects: they may attract criticism they don't serve simply because someone's expectations are not fully satisfied.