First of all, the reception of color and sound was not as rosy a picture as Ian paints it. Turner Classic Movies had two separate documentaries on those issues, and though I missed the one on color, sound was met with trepidation, and they hinted that it was the same for color (they were shown back-to-back with a preview in between then I went out). A lot of 'artistic' directors refused to use sound in their films the guy (can't believe I can't remember his name) that always wears a bowler hat and has a mustache in the most popular silent films continued to make silent films for years after the introduction of sound despite studios insistance movies be made with sound. There was also the problem that adding live sound (as opposed to a recorded track) was expensive.
3D, like all technology is not as good in its infancy as it will be on a few years. James Cameron did a fantastic job on Avatar, and next year's movies are going to blow it away, visually. As Ian inadvertantly stated with his CG examples, visuals are important to movies. Maybe seeing a character in 3D is not the greatest, but a good explosion, bullet, or other such flying object does add greatly to the movie, and I do recall the 3D scenes I've seen in 3D; it makes them a lot more memorable.
For the people who don't want to wear glasses, think of them as the price of early adoption, glasses-free is coming, it just has a few hurdles to cross. Also, while $900 for a TV (or anything besides a life saving surgery which unfortunately would cost way more) is too much for me, something like 60% of the world was not adversely affected by the recession, and I really meant comparitively affordably, as in compared to HDTVs when they first came out.
And Unagi, in a few months a lot of people here will get the chance to not only shoot short 3D videos and show them off, hopefully that will make them see the benefit of 3D. I didn't produce it, but I have seen 3D surgical footage at a hospital in NYC few years ago.
Speaking of a few years ago... IMAX 3D.