I think it's a good thing for 99% of computer users to not be able to just run any random software they download off of the internet. Gatekeeper, XProtect, and notarization are unfortunately necessary in the hostile computing environment we live in today. Aunt Tilly will happily download "PhotoShop" from that sketchy Russian Warez site and infect her machine if these protections didn't exist.
For power users that know what they're doing it is trivial to just use something like Homebrew or to bypass these protections on a case by case basis as needed. I can also run software in a Linux VM quite easily as well for open source software that isn't well maintained on macOS.
Regarding the built in Apple apps, I’m not sure what is gained by removing them other than a negligible amount of disk space. If you remove them from the dock they become out of sight out of mind. Same thing with the pre populated widgets and tiles on Windows.
Linux is best because it lets you use your computer for whatever workflow you need.