preauth and the problems with it

Have I understood correct that require-preauth=true is default in 1.5.1 KDC?

* Whan changing the default, the new default maybe can be mentioned in
  the krb5.conf manual page?

* If preauth is now default for all principals and the
  requires-pre-auth flag i kindof allways there, can it be disabled
  for some users somehow? I mean the opposite to 
       kadmin -l modify -a requires-pre-auth user

* Preauth destroys a lot of useful error messages. Earlier users got
  useful error messages like "time skew too great". Nowadays all
  failures are reported as "preauth failed". That does not help our
  support folks at all.

Harald.

PS: And could some native speaker please try to figure out if it
    should be spelled pre-auth or preauth ;-) I think the majority
    vote in the heimdal source is for preauth.