It would be very useful to be able to define a first class content type in the CMS.
Currently in Matrix we do this with a standard page, a metadata schema, a paint layout and maybe a custom design. These aspects all need to be managed separately meaning lots of room for error. There's also no good simple end point for headless CMS capabilities.
If we had a concept of first class 'content types' in the CMS, that allowed content modelling, default templates, and a built in way to use it via API, it would be very useful to better model the kinds of structured content Squiz customers need to manage.