They could take notes from a typical gaming controller, in terms of the feel, without having to adopt the look. Button layout is EASY... on my viewsonic they are placed pretty nicely, for my needs
Observe:

The buttons could use minor adjusting, and the d-pad sucks (VERY weak, easy to press the wrong directions, etc.), but in terms of placement, I'm pretty happy with it.
Probably the single BEST thing about a PPC is its versitility. It is a VERY viable gaming platform.
N-gage is $200, and FAR more limited in scope than your typical PPC.
A decent PPC can run you about $200, as well... and I surmise this price will gradually drop.
You can expect to spend maybe $100 on a gameboy advance SP, as well... not quite as versitile as a PPC.
The PPC's I'll grant you have not YET come into their own... but it is MY feeling that it's a matter of time.
What is the market compared to what it was? I wonder... I also wonder about the ratio of owners to game players... probably much better than it was 5 years ago

Is it unrealistic to believe the numbers will grow enough to warrant better design in the controls (EVEN if it must maintain a professional appearane)? I don't think so. So far every person I have enountered who has inquired about my device has asked if I can play games on it.