Two things:

1. Hardcore DHTML hackers hate it
2. Everybody else loves it
3. Some people confuse it with soccer (Thanks, Anne!)

Why? Because we hardcore DHTML hackers have been doing this stuff for years, but it never caught on. Combine that with a lot of hype, and you get negative reactions to the term. Until Google put the principle to good use in Gmail. That is, the hardcore DHTML hackers it hired finally got to design a system which used it.

The attention which has been given to Ajax in the past months has largely affected… designers. UI designers, such as Duntan Orchard and Derek Powazek. But also in the back end: Ajax got included in RubyOnRails a month after the original Adaptive Parth article. These are people who haven’t been hanging around in the DHTML communities of yore [1].

The question is, why? I don’t really know [2], but I have the feeling it’s because the DHTML hackers never got to design the systems, and as such couldn’t show their knowledge and ideas. XMLHttpRequest has been here since IE 5.0, after all.