[skissane]

> 1. It could have and still could be fixed

Microsoft actually tried to fix it in DOS 2.0 with SWITCHCHAR. In CONFIG.SYS, you could specify SWITCHCHAR=/ or SWITCHCHAR=-, and then there was an API (INT 21,37) programs could call to find out which to use.

However, they pulled this feature from the 2.0 documentation, and then mostly removed it in 3.0 (some vestiges remained, but it was non-functional). I think the big problem they faced was that while programs shipped with DOS would respect the SWITCHCHAR setting, third-party programs wouldn't (at least until new versions using that API were released). I think they found out that it was too late and all too hard due to the backward compatibility constraints with the already (even by then) vast base of existing DOS software.