In reply to Kathleen Clohessy.

Strangely enough most people believe that the customizer is not powerful enough and that it can't handle the things that they think they need.
All of the above assumptions are wrong.
The customizer IS powerful.
It can be extended to do whatever one needs to do.
It is written a lot better than any other options framework I've seen out there, and it's guaranteed to be supported, maintained and improved for years.
What's not to like?
The only thing that I see here is that people just don't like it when change happens.
This is a good change and will help improve the future for all themes.

I'm sure the "powerful themes" you mention above can easily be converted to use the Customizer, and when they do they will be better than ever.

Just give this a chance. :)