I'm also working on a Chrome and Firefox extension which uses Craigslist as a data source, and this is my understanding as well
I think that rich client-side js apps packaged as browser extensions offer some interesting opportunities in general - being able to behave more like a normal client, instead of a giant aggregation host, allowing you to avoid angering services like Craigslist, being able to ask the user for permissions for increased localstorage limits (the default in most browsers is a measly 5mb) and the ability to do cross-domain ajax requests, etc.