Just to say, there are always ways to deal with what you describe. For /bin/bash, create a symlink from /bin/bash to bash:

  system.activationScripts.binbash = ''
    mkdir -m 0755 -p /bin
    ln -sfn ${pkgs.bash}/bin/bash /bin/.bash.tmp
    mv /bin/.bash.tmp /bin/bash # atomically replace /bin/bash
  '';

For python, you're best off using a virtualenv anyways. For proprietary binaries, you can almost always get them to run using steam-run. But the nicer way is a wrapper script to set up LD_LIBRARY_PATH, or custom derivation to patch their ld lib paths.

Yeah it requires some elbow grease sometimes, but what distribution doesn't? Maybe Fedora/Ubuntu? I think the pain really is all that prior Linux knowledge is non-transferable and you have to learn how to fix things in the Nix way.