They may one day. But it's a big computational overhead from straight curling to running a JS VM for everything. Right now SPAs are still a minority on the web. But I guess the question is will you wait for Google to support your site and lose out on the awesomeness of single page applications?
I don't know the specifics, but they already have been for years (at least to some extent). Several of my clients have found content deep inside public-facing client-side apps indexed in situations where we didn't care if it was indexed, but assumed it wouldn't/couldn't be.
Do you have any examples? Because I've been building single page apps for 2 years, and none of it is indexed. Also indexing for search is not the only thing, sometimes clients need google adverts, which require the google media bot check your site's content. One of my clients could not get any data out, and the site could not get approved by Google for the adverts. But with SnapSearch, the google media bot was able to extract the necessary information.
Check your google webmaster tools, and you can force a scrape from google bots, and you can see that SPA sites are not discoverable.
I can't share the specific examples, unfortunately.
That's right that if you force a googlebot request from the webmaster tools, it's essentially just how the basic googlebot would wget a page on your site. We know they're doing more than that though, because it would be trivial to hide cloaking and malware from Google if that's the only tool they used for scraping.
What Google actually does for crawling content seems to be a bit more nuanced. If you watch the server-side logs on a site that Google crawls often, you'll sometimes see a pattern of googlebot crawling a page and then an immediate subsequent request from a Google IP from a Chrome UA. I'm sure that's partially just to assess malware/cloaking, but it's probably also related to developments like this one: https://twitter.com/mattcutts/status/131425949597179904
They're definitely doing more than just the ?_escaped_fragment_ rigamarole that almost no one uses.
Fair point about the AdSense crawler though. It seems to be just about as dumb as a rock in my experience.
