The thing that caught my attention the most about this wasn't the size of the code or whatever, but the fact that they want to make it highly customizable. It's a pain.

I'm sure there's a good example of TinyMCE finely-customized to fit an interface beautifuly and I'm sure someone here will produce said example, but most of the places where I see a WYSIWYG editor, it looks kind of out of place, this is very important to some designers (I think)