No need to be sorry at all 😄 You share the same views on the keyboard as others and it's not a hostile thing to say. Being able to choose your own keyboard isn't an issue, benefit of GrapheneOS is you can use your own apps you trust.
A mobile OS of this size is a large undertaking, maintaining it with fast, weekly updates, porting Android patches and doing community/support takes up a lot of time, it can be more work than adding features we desire. We strongly care about usability and app compatibility, but it's understandable GrapheneOS cannot compete against multibillion dollar companies with a huge budget on user experience. The community of users is our twelfth man.
In the best future all the AOSP sample apps that come bundled with the OS would be replaced with better, modern apps, like the keyboard, gallery, file manager etc. But, there'd have to be a developer who can make each one. There's a huge amount of additional work to do on improving privacy and security which obviously has a priority.