One major reason to stick with 1.45 is mod compatibility. Many total conversion mods (Promods, RusMap, EAA) were perfectly stable on 1.45 before updating to 1.46/1.47.
Required patches for newer DLCs:
So version 1.45 won’t support: West Balkans, Kansas, Oklahoma, Nebraska (ETS2 doesn't have US states – that’s ATS). Download Ets2 1.45 Full Dlc
Steam automatically updates ETS2 to the latest version, but you can revert to 1.45. One major reason to stick with 1
Steps to legally play ETS2 1.45 with your owned DLC: Required patches for newer DLCs: