I think the issue is mainly with the principle of asking someone to run a shell script to do an installation. People who are security-minded, will check the script first. Those same people know that most won't do that.
The world is an even scarier place when you trust the wrong person
Every piece of software relies to some degree on other software. Similarly, every person relies to some degree on other people. As long as you don't find yourselves in a race to the bottom of the barrel, things should be okay.