Considering that Rockbox is both open source and themable, one could reasonably assume that if a great enough percentage of people preferred the Cowon design, both themes and possibly custom builds changing things to be more like it would be showing up.
Honestly though, if you prefer Cowon's design and/or features, why not just use Cowon's firmware. If you already prefer it, that means it must have more good things about it, so try to convince them to add in the fewer things that they're missing.
