why does nobody ever read installation instructions
Umm, I think he or she IS following the instructions. But requiring to compile another program excludes most ordinary Inkscape users from using this extension, in my opinion.
Speaking only for myself,
I did read the instructions! Those instructions don't say 'you can install it this way or that way if you want to'. It doesn't say 'you must install both'. It doesn't say what Auto Trace is for. It only gives instructions for installing both, without any indication what the Auto Trace part is for, whether it's optional or whether it's required.
To me, it looks for all the world like the Auto Trace part is required. It's only because I couldn't figure out how to install the Auto Trace part, and almost on a whim I tried using it without having installed Auto Trace. To me, there is no way for a user to know whether the Auto Trace part is required or optional or what it's for or what happens if you don't install it.
Are you implying that something in those instructions tells us what Auto Trace is for, and why it's needed or not needed? "this applications searches there" is the clue? What the heck does that mean? Which application searches - the main extension or Auto Trace? Searches for what, why? And what does searching have to do with centerline trace?
But for me, the bottom line is that most Inkscape users can't compile any program. I have no idea how many will think like I did "well
maybe it will work without Auto Trace" and try it anyway. Probably not very many, I would guess.