Of course, there still are user interface issues - but they are really more similar to the traditional model of system design than layout on paper. Style as it is used today just satisfies the designers. But in reality, it communicates an experience. The challenge is designing a user experience that is the same over all different devices - without graphic style. If nothing else, you will have to contend with voice menues.
Presentation is less important than navigation.
The browser is the user interface. A standard CSS style could be burnt into the device - which means it takes no over the air capacity. The browser design space is the user interface to the information. Future WAP styling mechanisms should use standards. As you understand, the important thing is not the style as much as what is behind the style.