[zck]

Imagine the added complexity that you would require to do that -- you'd need to have more hardware than a general-purpose search engine. It's also complicated to precalculate anything, as there aren't a list of regexes that are more likely to be entered, unlike text (a dictionary).

Who would use the regex search? Only programmers. So your market is tiny compared to a general-purpose search engine.

So more expensive queries that are harder to code up for many fewer people? Sounds like a losing bet.