"Well, on the other hand, okay, let's not argue about whether a such software
is a free software . A software without sufficient configuration is not
respecting user's freedom anyway."
You say to not talk of it, and then immediately re-assert your argument
again. A free program is free (and therefore respects your freedom)
regardless of how configurable it is. Any other argument is going to be a
non-starter, sorry.
"What's the reason that NetworkManager provides few configuration
opportunities?"
No one has taken the time to do it? Free software isn't perfect.
Free software is sometimes uglier than proprietary software. It is sometimes
more expensive than proprietary software. It is sometimes less functional
than proprietary software. Free software is sometimes buggier than
proprietary software. (Sometimes people say free software has more than our
fair share of bugs.) But it's always going to be free. To say otherwise is
disingenuous. To *think* otherwise is to buy in to the promise of "open
source" which promises better quality, higher reliability, etc. but this
isn't always the case. See:
https://mako.cc/writing/hill-when_free_software_isnt_better.html
