Thanks for your suggestion. We are considering such implementation.The feature is not scheduled yet, but it should be done for all content types similar to page templates where you can see how many pages use your this template.
All the best,
the Telerik team
Do you want to have your say in the Sitefinity development roadmap? Do you want to know when a feature you requested is added or when a bug fixed? Explore the Telerik Public Issue Tracking
system and vote to affect the priority of the items