You're being facetious, but I think a small penis would decrease property values. That's part of why I want a small dick registry. People have a right to know if they are living next door to someone with a small penis.
On that note, a small penis tax isn't that bad of an idea. It could be used to pay for the registry and research into genetic engineering to eliminate the small penis for good.
I'm curious as to how penis sizes would be classified. We all know that the erect length is the stated size of a penis, occasionally with girth for the thorough, but in day to day life we generally don't go around engorged. So my question is would there be a class differents between the growers and the showers? Would a 7 inch that grew to a 9 inch be more valued than a 5 inch that grew to 10? I'd think in day to day life the shower would be more advantagous and prized above the grower, unless laws were made to include certified penis lengths in our job applications. (actually perhaps having them on drivers licences would be the way do go as it's our most often used ID and could be measured when we go for our licence photo's)
Also the size of balls cannot be understated in their importance too. A pair of raisins under your soft python is hardly gonna fill out your pants the way a set of juicy mangos will. I'd even go so far as to say a huge set of balls could make up for only having an average cock of 7-8 inches.
I think there should definitely be made an easier way to identify those with less than adequate junk though.