Well there are hundreds of developers not having 64-bit version available for long time, take Firefox and Adobe Flash f.e. Even if these work without problems on Windows x64, it doesn't seem like they are in a hurry to work on the 64-bit side. There is a x64 version of Firefox, but it is a inofficial build afaik. With Firefox, you would need to have all add-ons coded for x64 separately too.
Overall I agree with you, but the transition does take time it seems. Many applications don't benefit anything practically from switching to x64. For others even I have noticed speed improvements (like for 7-Zip x64).
What Microsoft needs to do is promote their x64 versions harder, it is Microsoft that can make the change go faster. I hope they do that with Windows 7.
There's nothing to me that I'm really noticing as being "way faster" that I cannot attribute to doing a clean install. Then again, my machine wasn't exactly the slowest machine in the world in the first place.
I do like the explorer changes, though.
Its explained in the video what the enhancements to performance are about, the performance improvments are really more future oriented. Its not really going to be "alot faster" for most of the existing users.
(he also talks about vista compatability mode for drivers, and what it means)