No, CL has had explicit notices posted regarding prostitution for a long time and has actively moderated for overt prostitution. You can't compare now, but if you compare ads on Craigslist to other personals / services websites like Backpage, Craigslist has been quite PG-13-rated for a long time and at least forces posters to be a bit more subtle. The "massage" section is actually mostly pleasantly legit in my experience, assuming you're not in a big city.
I wouldn't be so quick to call it self-evident that there was a better response than to immediately shut down their classifieds.
I'm sure there's more to do than just flicking a "filter prostitution: yes / no" switch on their admin panel.