Content Definition menu missing in Orchard 1.7

One of the changes in Orchard 1.7.x is that the functionality to create custom content types was moved from a tab in the "content" section to a separate menu item in the dashboard. So far, so good, but after setting up a fresh blog on Orchard, this menu item was missing in my installation.

After going through logfiles looking for installation errors and trying to change the authorization for the admin user, I found out that this option is enabled by toggling the Contents module from "disabled" to "enabled". Interestingly this is not required when starting a new site using the "default" recipy: in that case, the Content Definition menu option is simply there.