Apologies if this is not actually a bug and more of a suggestion.
With Classic coming out I don’t know if there will be a distinction in the quicklaunch menu or if they’re just going to overlap. Just to clarify, what I mean by quicklaunch is the icon shortcut in the Windows Taskbar next to the clock. (image of the quicklaunch menu for reference) imgurdotcom/FkSizY5
If they’re going to overlap, then I believe that it should launch the most recently played version of the game. How it currently works is if you have Retail installed as well as Classic then it will always launch Retail.
Making a shortcut to Classic (from the bnet app Classic options menu) just opens the bnet app to the Classic window. Making a shortcut to the Classic WoW.exe loses the automatic login from the launcher and requires inputting your password.