I dug out part of the mail.  A lot was unprintable, but here's a section:

+The presupposition of all these standards as that the big market is the
+device driver developer (the VAR). This is no longer the case as the
+hardware guys have completely given up on software folks figuring which
+end of the pants to try and unzip and have gone off to do I2O instead.
+Anything that isn't tackled this way is bashed into existing major device
+frameworks which would now cost more than it would be worth to try and
+achieve a common pluggable base. And anyway, attempts to rationalize the
+framework do nothing to address the different semantics that different
+platforms ultimately enforce.

Not entirely a rational argument, but basically it's "What's in it for us?".

Frankly, we'd be better off revisiting the CAM in NetBSD argument first....

-matt