On Wed, 13 Jul 2011 23:07:52 +0200, Valentin Plechinger <v.plechinger@gmail.com> wrote:
> Didn't know that, still if it works perfectly why change it?

Because it won't, at some point in the future. By updating it when
learning it's deprecated, he saves himself the trouble of figuring out
why his configuration suddenly stopped working. (Which was still caused
here, but by not checking if the change actually had the desired
effect).

At any rate, I guess the docstring for default-major-mode possibly
should say more than just "use `major-mode' instead" though.