With your help, I'd like to try a thought experiment.
Lets imagine for a moment that the native Win32 compatibility was perfect. All the modules, all the functionality, they all Just Work.
Would you still want to use cygwin? It cygwin "just" a crutch to get around things that doesn't work natively? Or do you (personally) really need it for something else? Or do you just really like using it? Is it a fix for your Unix withdrawal syndrome?
Or would you be happy to see it gone if it wasn't needed to make certain modules work more easily?