The NCAA's approach is completely unsurprising, and also appropriate.
The NCAA is an organization that was formed by, and ultimately answers to, it's membership. As such, unless the member schools get together and say "NCAA, we'd like you to come up with guidelines for all of us to follow", then the NCAA isn't going to step up and do it on their own, because they know they don't have a mandate from their members to do so. The NCAA only has exactly as much power as the member schools give them.
This is different from recruiting and eligibility guidelines, of course, because the members did in fact mandate that the NCAA define, enforce, and investigate these in the interest of "fair play".