From the items above I think we can see that this shift is more than simple trendiness or the "flavor of the month". Well - fisheye overhead photography was just trendiness that got tired fast.
But many of the items mentioned simply don't work well in delivering content to the end user, and people who watched their stats learned this. Some are slow, some are graceless and look "cheap", some confuse users.
The key to good design is does it support the delivery of information. People who are tuned in to this will drop what they see isn't working.
And then there's the fact that any innovation that is used too frequently becomes boring so people tune it out (as in banner blindness). Again, it worked for a while but it stopped working. I think designers do well to focus on how to support the site's information rather than trying to attract attention to design itself.