Not just me then. I hated Windows 10 Calc so much, that I copied over calc.exe from Windows 7 and made the following registry change:

  HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\App Paths\CALC.EXE

  (Default)   C:\<PATH-TO-WINDOWS7-CALC>\calc.exe
  Path        C:\<PATH-TO-WINDOWS7-CALC>

Presto! Whenever you Win+R, Calc.exe - you get the Windows 7 one instead. This would work for any of the other apps listed in 'App Paths' too (or you can add your own).

There's redbaron, which provides a full syntax tree, and is designed for making such changes: https://github.com/PyCQA/redbaron