Problem - you are talking about changing registrar, but in
reality you describe changing of domain owner.
Yes you are right in that often a number of domain name variables change
at around the same time.
Why (what for) is it allowed to transfer from one registrar
to another with changing NS records and other owner information?
Usually it is NS records that change, as a transfer can be associated
with moving a domain name to a new service provider for email or web
hosting. It is often the change in other services that prompts the
transfer request in the first place.
Why don't separate this 2 events - changing registrar, and
changing domain owner/information? Is it any need in reality
changing registrar with simultaneous changing domain information?
I agree with respect to "ownership" change that this should be separated
by some time period from registrar transfer. Note that only the
registrar transfer process is regulated by the ICANN agreements.
Apart from changes in the identity of the legal holder of the domain
name agreement, other details such as postal address, phone numbers and
email addresses are often updated at the time of customer contact with
respect to the transfer. Usually this information represents the most
up-to-date contact information.
What should happen in normal situation:
- someone requested transfer of domain (without real authorisation);
- even if all checks pass and transfer was allowed, new
registrar should maintain the same NS and other information
as old one, so no real damage could happen;
- domain owner received e-mail, see frauded transfer and
disputed it (having domain in working condition on the new registrar);
- new registrar OR old registrar OR VeriSign roll back transaction.
This is effectively what happened in the panix.com case. As soon as
facts were verified the NS records were rolled back by the gaining
registrar to their previous state. The issue was that it took hours to
occur. It is a separate discussion as to whether the registry operator
(Verisign in this case) should do this roll back in the case of a
network outage in the absence of instructions from registrars.