Personally i would have to say, if a frontend doesn't offer me the ability to reskin the UI i wouldn't even waste my time downloading it to try it out. The chances of it doing everything i want it to do, the way i want it to do it are very slim and taking away the ability of me correcting that issue myself means it will never do what i want it to the way i want.
I think many people do want a frontend that "just works" (many of them do, Centrafuse being a good example), but i think you are making a mistake in thinking that skinning an app is a end user requirement of any of the frontends available or somehow a negative aspect. This is a feature and i would argue probably the most important feature second only to the application itself.
Take away the ability to change the way the application looks and functions and you also take away any community that would potentially stand behind and support the app. You are also taking a gamble that your art, and ideas of how the application should look and be layed out will be good enough to satisfy a large number of people or anybody other than you. Many people are very picky on what there frontend looks like down to wanting the colors to match the interior colors of there car.
I dont want you to take what i say as a deterant to what you want to do, this is just one persons opinion and nothing more.
With that said, im still interested in the project you are working on, I thought your last idea was pretty good with the only downside being .net3.0/winfx.
So how about posting some screenshots ?