I think the answer in this may also lie in what type of domainer you are. Many just want the ease of parking their domians via PPC and forgetting about them. If they see a low CTR on a name, they look at the keywords and adjust them and that's about it.
For others, PPC is just a short term hold until they want to move on to development. To each is own. If anything I tend to agree with Edwin in that if CTR remains low, even with tweaking, development may be the only way to get potential out of a names traffic.
For me, I'm a hunter and gatherer...then park at PPC. When in the future, the prices and supply of traffic domains make them unattractive, then maybe selective development of my portfolio may be an option (but that sounds like work).
Canuck