And what stops you to install those?

As I am using omp (along with CSSU), I can tell you it still lacks some functionality compared to stock (like you can't share a video by using service on omp, while you can on stock), there are unresolved bug in it (reported on omp thread), so it would be a regression if it is included in cssu.

Also, such complicated pieces of SW need an active maintainer and with all my respect to gidzzz, he is not very active here lately. So - who will support those if we push them into all the users throats and new bug get discovered? With only 2 or 3 developers remaining to support the OS, I believe it is more sane to use that manpower to fix critical bugs, to backport CVEs, etc., than replacing a perfectly working applications, just for the sake of it.