Unfortunately, in the interests of user convenience, in not having to use two passwords (root & the logged in user), Ubuntu and distributions based on that model make the first user an almost root user; except you do have to use sudo as a prefix in order to do an administrative (root like) task, and the password is your first created user password ---so we are already in danger just from the normal login process; but Mint and Ubuntu and Debian all disable the root account, so the full power is not available, only I don't know exactly what that limitation is between the pseudo root (first user account) and the real root (root account)
This is an argument that has been on going since "sudo" came into widespread use. While I can see some merit on both sides of the argument, let me give an opposing view for the sake of balance.
The first user isn't "an almost root user." S/he, by default, is in the sudo group, but that is far from being "an almost root." Being able to use sudo doesn't mean you have in anyway been compromised by logging in. By-the-way, Debian sid doesn't disable the root password. It is assigned during the install process.
If you use sudo to start a program or do some other task, your root privileges are limited to the tasks that have been registered by default to sudo. Some would say it is safer to use sudo because of this limitation. If you use "sudo su" you have root privileges, but with the user's profile. If you use "sudo su -i" you use the root profile. "sudo su -i" is true root, just as if you had a root password set in a more traditional distro and had used it to log in as root.
If you have sudo loaded on a more traditional distro with a separate root, which many distros do by default, one could make the argument that it is less secure with two passwords. Check some of the more traditional distros. You will be surprised how many have sudo installed. In an infinite range of passwords, either of the two passwords will break securiety.
Also, an argument can be made that it is easier to remember one good password than two. As an example, your user password could be: "Mychildren'sages+10areAmy46,Sarah36,&Catherine34.". I would love to see you break that one.
Of course you could shorten it and still be ok, but that is an example of one good password that can be easily remembered. After your system is setup and working ok you don't need to use it much anyway. Of course if you want a simple password to do your setup with fine, use something easier to type. Then when you are ready, change it to something much harder to break.
Despite that, Linux has proven quite safe as a system, even if you did run as root
This is categorically untrue. Running an X session in root is tantamount to OS suicide. This must be a typo on your part. I can't believe you think that is true.
The other side of the story.