For what it's worth, I sent a few days ago some feedback to Amazon (UK) about the PW and the general "Kindle experience". One of the things I mentioned was the inability to turn off the publisher font in some books. I have the right tools in Calibre to change that, but given that I have quite a large "to read" pile anyway, what I now do when I buy a book is to immediately check whether the font is locked or not. If it is, then I go with a return/refund. There's plenty of books that don't have that issue, so I'll buy and read those instead
Edit: for the UK, the email is
kindle-feedback@amazon.co.uk