Craigslist is a good indicator of the world at large in regards to fraud and such.
You could make it "better", but you would find the overhead required to make it better would also require a lot more resources to operate properly.
So, you'd have to charge for more things, which would likely lead to decreased usage and accessibility to society at large, which ends up with the exact inverse of what you were trying to do.
What do you mean by "a good indicator ... to fraud and such?" Are you implying that fraud should be accepted as just something inherent in society and shouldn't be something we try and prevent? Also, I would contend that the facebook marketplace has less fraud than the craigslist marketplace, thus giving craigslist something they could shoot for.
Also, I'd like to refine "better" to "safer". General feel and aesthetics are subjective where as safety is objective.
Craigslist leaves millions, if not billions, of dollars on the table every year, it would only take the inclusion of one or two more markets in their pay-to-post-real-estate stream in order to hire some really smart developers to come up with smart and subtle fraud prevention mechanisms. It's possible for them to raise some dough for this issue without harming the culture, so why shouldn't they?
Craigslist is a fairly unfiltered portal into society. It is not based on relationships like facebook, it does not require more extensive seller verification like ebay. It is basically the newspaper classifieds in an online format with only a twinge of technology sprinkled in.
Craigslist is easy to use and the primarily text-driven approach means it is accessible to even users on dial-up connections (and although you might think this rare, I still know people in the US who have no viable high-speed Internet options and are using dial-up).
Fraud is, IMO, inherent in society. Manipulative and creative people have been taking advantage of trusting or less educated people since man first implemented a monetary instrument.
I think part of the make-a-better-Craigslist camp is similar to some of the confusion around the mint.com sale... Not everybody has the same motivations... I don't think Craigslist wants to be the best/safest/most-diverse online classifieds system. I think they want to be the easiest, simplest, I-can-go-home-at-night-and-not-be-bothered online classifieds system. There are many things they could do to be "better", but I don't believe the cost and complexity is worth the impact on the lives of the employees and the business overall.
There is a market opportunity for an improved Craigslist, but it's a little bit of an end-of-the-rainbow pursuit.
You could make it "better", but you would find the overhead required to make it better would also require a lot more resources to operate properly.
So, you'd have to charge for more things, which would likely lead to decreased usage and accessibility to society at large, which ends up with the exact inverse of what you were trying to do.