I don't understand. What would be the correct default install location?
And Windows allows side-by-side installs of 64- and 32-bit versions of the same software; so installers should be aware of 'C:\Program Files (x86)' and 'C:\Program Files'; the first is for 32-bit programs on 64-bit machines.
I've put junk in the root of my drives since before Windows 95. Installers that default to putting junk C:\Progra~1 are what's awful.