For a long time now the only complaint I've really had with WordPress is that wp is quite literally crammed down our throats at every corner.
It's not that I have any shame in using WordPress, I love WordPress... and I'd love to express that in my own way.
I've always wished that wp-admin, wp-login.php, wp-content and so on were presented more professionally and simply as admin, login.php, content etc.
Also, I wish the code was cleaner, not so riddled with programmer comments. I understand that's helpful for beginners so perhaps I'm suggesting a developer version and if it has to be paid so be it.
I'd be happy to pay $1 every time a new developer version was available to upgrade my websites. On the users end that would be nothing, but on WordPress' end that would be substantial. There would still be the free version of course, but also an optional professional/clean version.
You could argue that you could clean it all up yourself, but we all know that's a lost cause with the ever updating WordPress.
I can't be the only one that's wanted this for some time now.