The "standard of comment quality that makes LWN a good forum" excludes repetitive mindless drivel. We come here not only because it's less of a flamefest than other sites but because it usually has more intelligent discussion rather than wasting everybody's time by rehashing the same brainless argument fodder that people have been spewing for decades.
Everybody here has heard the merits of the Stallman kool-aid preached plenty of times, and either they drank it or they deliberately decided not to. By rehashing all the same old "GPL is the Only True License, LGPL is only a stepping stone in the Seven-Year Plan and anyone who advocates its use outside of that role is an enemy of the Party" propaganda you aren't going to convince anyone around here.
There are zero frontend projects that would have been open-source if libVLC had kept its old license but will now be closed. That argument is a total red herring. Further, since there are plenty of other video libraries out there, no other apps would have been enticed to use a GPL-compatible license just to be able to use libVLC either.
Contrary to your claim, anybody who uses libVLC will still have to release any modifications, and libVLC will have more users, so code contributions are a reason in the LGPL's favor. (Even MIT/BSD licensed libraries see most users contribute back their changes though in such a case it's not required.)
The only thing you said that has any semblance of truth about it is that being able to choose libVLC over other already-available video libraries might conceivably make life easier for some proprietary software developer out there. The horrors!
Choosing an unsuitable license and shooting yourself in the foot just to spite some hypothetical proprietary developer is not going to do anything to advance users' or developers' freedom.