I appreciate your frustrations too. However, since there are a few designers in the core team, we have been pushing for total control on every pixel that DNN outputs to the scree.
However, this is not an easy task since there are number of layers at work here. Especially with the limitations of the .Net 1.1 framework itself and the legacy stuff from IBS. I think DNN has gone a long way since its original IBS background thanks to mainly the thanks less inner core team efforts, and I believe right now we have a framework that has given more control to designers than any other CMS that I have come across.
That does not mean that the work has stopped here, there are more to be done and there are a lot that is being done.
Since each module runs on its own therefore each module to take its own path in optimization and getting ride of the unnecessary padding and sorting out the css classes available in the core. In my custom skinning work, when a client asks to skin a third-party module right now we do take it apart and make it work. But it does mean to change the source right now.
I am sure and hopping a lot will change with .net 2 and the work towards DNN4 will improve things further. in the mean time we have to just work within the boundaries set by the framework and the forthcoming task of making dnn compatible to ASP.NET 2 which in turn should give more power to the designer.
Salar