For me it's more that the older interfaces do what
they do very well. I hate
having to change technology just for the sake of it, particularly if that
involves a leap in complexity along the way.
That's much my attitude too, and not just about interfaces. I see no
reason at all to replace a solution that works with one that's untested
(at least by me) which may or may not have advantages (and often, alas,
has problems). If I have something that does the job I want it to, then
I'll stick with it.
-tony