For many years it has been customary in Kali Linux to use the default root access policy for the user, which is inherited from BackTrack Linux. On December 31, 2019, the developers of Kali Linux decided to switch to a more "classic" policy - the lack of root rights to the user in the default session. The change will be implemented in the 2020.1 release of the distribution, but if you wish, you can test it now by downloading one of the nightly or weekly builds.
A bit of history and theory
Originally based on Slackware, BackTrack Linux was nothing but a huge set of pentesting tools. Since many of these tools required root rights, and the distribution was only meant to be run in Live mode from disk, the most obvious and simple solution was to make the default user root.
Over time, the popularity of the distribution grew, and users began to install it on hardware, instead of simply using it in "boot disk" mode. Then, in February 2011, it was decided to switch from Slackware to Ubuntu so that users would have less problems and be able to upgrade in a timely manner. Some time later, Debian Linux formed the basis of Kali.
Although developers do not encourage the use of the Kali distribution as the main OS, now for some reason many users do this, even if they do not use the distribution kit for its intended purpose - for pentesting. Remarkably, some members of the distribution's development team do this as well.
With this use, default root rights are more evil than good, which is why it was decided to switch to the βtraditionalβ security model - the default user without root rights.
The developers are afraid that such a solution will lead to a whole bunch of error messages, but the safety of using the distribution is still more important.
Source: linux.org.ru