This is good because I always ended up removing the defualt user and creating another or just using root. You can always mount the SD card partition and put yo

This is good because I always ended up removing the defualt user and creating another or just using root. You can always mount the SD card partition and put your ssh key into /root to log in with that. An improvement could be to also load ssh key from the /boot partition so also windows/mac users could do that easily. By the way using root with an ssh key is fine and not a problem in terms of security.