I think you might not fully understand what the su command does in linux, and what bricked means for that matter. You would have to try very hard to corrupt your bootloader, but if someone really wanted to be a dick and write a bash script to ruin every piece of softwate on your phone, you can still recover now that we are fortunate enough to have our sbf tool.
You are fully correct about your point though. If you ran a linux distro, you would have already had this engrained on the surface of your brain, never give root access to anything unless you know what it will do and what you are doing, never login as root, and never give out your root pw, even if your mother's life depended on it. I don't understand android enough to know why there is no root pw, or if a sudoers script could help with security.
But some people have no desire to learn how to do something, and are the same people who post threads about not having a clue what to do when something doesn't work, and expect their hand help every step of the way. Nothing will ever prevent that though.
Tried to be concise about it, and not to sound like I'm ranting.
Couldn't help but think of this xkcd, hope it gives someone a laugh.
xkcd: Tech Support Cheat Sheet