Google is paying Wikipedia through "Wikimedia Enterprise." If Wikipedia weren't able to sucker people into thinking that they're poverty-stricken, Google would probably prop it up like they do Firefox.
If I were establishing a "crawl budget", it would be adjusted by value. If you're consistently serving up hits as I crawl, I'll keep crawling. If it's a hundred pages that will basically never be a first page result, maybe not.
Wikipedia had a long tail of low-value content, but even the low-value content tends to be among the highest value for its given focus. e.g., I don't know how many people search "Danish trade monopoly in Iceland", and the Wikipedia article on it isn't fantastic, but it's a pretty good start[0]. Good enough to serve up as the main snippet on Google.
Purely speculating, Wikipedia has a huge number of inbound links (likely many more than CNet or even than more popular sites) which crawler allocation might be proportionate to. Even if it only crawled pages that had a specific link from an external site, that would be enough for Google to get pretty good coverage of Wikipedia.