Long story short: these changes are not part of OpenWrt mostly because I never sent them out there.
Most improvements are listed in the post #1. Some of these very same improvements are controversial like unlocking the CPU frequencies and are very unlikely to make it to OpenWrt.
They already rejected my compressed-memory initiative for some weird and rather not important reasons. We have to understand that OpenWrt has its own political standpoint as well.
The main disadvantage is that people may not use unbound which is installed and setup by default and they will have to remove them manually.
In my opinion those changes I made are fairly good. They are slim which means that for the normal user this is like OpenWrt but better (or even usable if you need vlans, feature that can't be used in vanilla OpenWrt).
Those changes have already a long history from myself and some users running it since 2019. That means that you can safely trust that unlocking the CPU frequencies won't burn your device anytime soon as OpenWrt developers may argue.
Since those changes are very very very slim you can read the forum to check the differences between 19.07 and 21.02. Just add "working vlans, faster, preinstalled software, and better memory management" to the list and you are good to go.
@kramsac you can find the differences here: