People who were using [WPCR_INSERT] on 2.x without actually enabling the plugin on the page were exploiting a bug in 2.x where [WPCR_INSERT] appears to have psuedo-enabled the plugin for the page, but the checkbox is what should have enabled it.
Going to 3.0, the bug was fixed since WordPress now internally needs to know which pages the plugin was enabled on, and just having the shortcode inside of the page content isn’t the way WordPress does that.
A “fix” could be made by somebody. You would need to make something that goes through all of your post content searching for [WPCR_INSERT] and sets the meta for that page to have WPCR enabled on the page. If somebody wants to do this, go for it ?? If not, I’ll get around to it as soon as I can.