It's not that simple. PM is trying to profit by innovating, CL is trying to profit by maintaining a monopoly position. They're entitled (legally) to do that, but they're not entitled to do so without losing the goodwill that they rely on for customers to give them their listing for free.
That's an extremely concise, and (I believe), correct, point.
The question is whether or not there's room for a craigslist clone, particularly one that can succeed by sharing its data openly with third-parties.
In truth, I'm doubtful. My reluctant conclusion is that there is, in fact, value in preventing the data from being spread across multiple interfaces and platforms, which itself could confuse users. This was essentially Twitter's stance when it came time to solidify their brand and reduce the number of clients.
There is real user value in knowing how their listing will be presented. I mean, if I'm listing a room for rent and "DruggieCriminalRoommateFinder" syndicates my listing, I'm probably not going to be happy with the response quality.
