Taters,
I generally agree with your position that function should be more important than form. As an example of this, I just bought a rather plain and unimpressive looking class D amp that has very impressive performance (Class D Audio SDS4440SC amp). But, while I am thrilled with it's sonics, I still wish it looked better.
On the other hand, I also agree with Stevecham that a product should be not only be well engineered, but well styled as well. Many try to minimize it, but pride of ownership is an important factor to most of us, especially in things like cars and audio equipment. We see and use these both on a daily basis and are reminded of any shortcomings in looks and performance on a daily basis, too.
Personally, if I was considering buying 2 amps and they were about the same price/warranty and their sound was equally good, I would not hesitate to buy the better looking amp. Of course, amp manufacturers probably have been aware of this human tendency for a long time.
Thanks,
Tim