It hurts me when people chose to keep things broken (Craigslist) for irrational reasons, especially when it wastes hours of time for millions of people.
It seems to me that Craig is trying to balance making CL wide-openly available to individual people while preventing a business ecology from growing on top of it. He is all for the latter, and really hates the former. In contrast EBay thrives on the business ecology it has created. (But then I think Craig is a socialist at heart -- and bless him for it!)
So, while I am sorry that a bunch of cool hacks got shut down, it might be a pretty reasonable decision on CL's part to cut off Yahoo Pipes. Plus, it's his site to do with it what he wants...
(There is some great interview with him in Wired that got linked here not too long ago.)
It's broken because the people who go out of their way to create software for craigslist aren't largely duplicating functionality.
Want a map view so you can see all the relevant listings in one view?
Want craigslist to deliberately filter the same text or picture used for different listed apartments or jobs so you don't waste your time or get scammed?
Want to search by squarefoot or by actual bedrooms or by picture?
Apple would say "There's an app for that." Craigslist says "screw you".
Have you ever heard of the network effect? Craigslist has such a lock on its market that you would have to have something extremely compelling to dislodge them. A few flashy maps and a web 2.0ish appearance wouldn't be nearly enough to do it.
Classified sites gain a regional dominance. Craigslist in canada for example, is only really dominant in vancouver, one of their biggest foreign markets. Kijiji is dominant in other towns.
Many apartment/house finding sites have these features: search pages with dozens of checkboxes and dropdowns, and equally complex data entry pages for the people listing the apartments/houses. Yet Craigslist dominates. Simplicity wins.
How are these people a threat to Craigslist business? The more people use its data, the more valuable it becomes to post to Craigslist, and the more market share Craigslist gains. Craigslist does not lose a dime because of third-party mash-up sites.