Anybody else lamenting the waning of the mp4 file format as an almost
defacto standard on the web (and elsewhere)? Why?

Well, for one, most of the tools we had for working on these files are now
useless, like tools to mux and demux the file, cut and edit the file, etc.
All those programs... I can't tell you how many times such mp4 tools have
come in handy for working with mp4 video files, like for cleaning up and
restoring the audio tracks from some Youtube clips, as just one example (and
boy do some of them need some work).

And two, and perhaps of more importance to most people, many TV sets won't
even play these new video formats - unlike the mp4 files. Sure, they can
still play mpg files, but that's pretty limiting, to say the least!

But I'll have to concede that mp4 was proprietary format, unlike webm and
its vp9 video codec, so here we are, whether we want it or not. I still
think it sucks. :-)