The "latter developments" in your example became huge over time from people experimenting with the new format. Your comparison doesn't make any argument against the format at all and it certainly doesn't serve up any points of contradiction as to why this is an invalid format.

I think if I was to make a comparison I would compare the use of 3D on Avatar to the use of surround sound on the original Star Wars. You can certainly apply everything you said regarding why 3D is not necessary to surround sound as well.

And lets not forget the most amazing reason for 3D - DARIO ARGENTO'S DRACULA 3D aka DARIO ARGENTO'S ASIA ARGENTO'S TITS PART V;