[metamemetics]

>For a web application, the code might make the entire thing operate, but it never affects the user the way the design or interface does.

Sounds like you're primarily talking about the backend PHP coding then? One option already mentioned is to learn a new way to develop backends that you find funner (ex. Python).

The other you should seriously consider is to team-up and form a partnership with someone who enjoys programming more. This way you focus primarily on User Interface which you seem more passionate about and have a friend whip out the backends. You will be able to tackle larger more exciting projects and your prior programming knowledge will make it easier for you integrate your design work with the developer's.