Photoshop has had the ability to use channels, curves, and path shapes since 5.0. A solid understanding of paths, curves and channels gives you all the vector-style capabilities you need to make static images. I mean, you have to use tools to make the shapes in a vector app as well, right?
I have found that 'vector' graphics as concept are something that most people don't need. They are based on mathmatically defined shapes. That is handy when you need to scale graphics, or animate or morph the finished work.
Beyond that, if you are gonna use the image for a wallaper, skin, etc., you are gonna have to rasterize it to make it a jpg or bmp, and all the benefits of the vector abilities are gone. I can see possibilites using vector shapes to flesh out the initial shape of the skin, but as I said, paths and channels can do as good a job, without an extra app.
The last wallpaper I made had 97 layers when I finished. A complex skin can have just as many. *IF* vector apps have am advantage in intitial design, I dunno if it is beneficial to trade that for the robust capabilities of raster apps when you are making the final rasterized images.