"The reason you need to run a 16 bit installer" is to display a nice "Tough luck, you need a 32-bit computer to install this" message to the user, instead of an ugly Windows error message.
This was important at the time. And the whole point of backward compatibility is to allowed old applications (written, compiled and packaged at that time) to work.
Even if the software is open-source and has been repackaged in the meantime, the old version you found on a long-forgotten CD rotting away in your basement doesn't have that. The Windows philosophy is to make sure that this one still works (which is a crazy goal IMO, but an interesting one).
The reason for this hack is that 32-bit software used 16-bit installers long after the switch to 32-bit. [0] This isn't a matter of supporting Windows 3.11-era software, more like Windows 9x or even XP.
This was important at the time. And the whole point of backward compatibility is to allowed old applications (written, compiled and packaged at that time) to work.
Even if the software is open-source and has been repackaged in the meantime, the old version you found on a long-forgotten CD rotting away in your basement doesn't have that. The Windows philosophy is to make sure that this one still works (which is a crazy goal IMO, but an interesting one).