There's a lot of practical reasons why someone wouldn't want one. There are foreign travel and contact reporting requirements and use of weed is forbidden. Some people may be uncomfortable with the level of scrutiny that investigators go through to find dirt on you (talking to neighbors, friends, and family even if you didn't put them down as references). Once your clearance lapses, you have no requirements other than the lifelong NDA you sign regarding the work you did which could hamper future job interviews somewhat if you can't talk about what you actually worked on. If you write a book, you usually need to get permission prior to publishing by submitting drafts to the government, especially if it's relevant to your work.

As for ethics, clearances go hand in hand in working with intelligence agencies, the department of defense, federal law enforcement or a few other departments either as a contractor or government employee. So if you are fundamentally opposed to what these groups do, maybe a job requiring a clearance isn't the best fit for you. There is another clearance called public trust that is very mild that may be required at places like the Treasury or NASA. Basically if you don't want a clearance, avoid working for the government.

I bowed out of the process. I just couldn't quite figure out how to reconcile what was asked of me.

Don't be around people in possession of illegal drugs. Ok, well grandpa died and I know for sure his oxy is in his medicine cabinet. Grandma hasn't thrown that away. You're not really allowed to do that, ya know?

I understand why the rules are the way they are. I understand that they would not care about that situation. The FBI agent asked rather pointed questions about, am I the kind of person who follows the rules when no one is watching. I feel pretty comfortable saying I do. I feel pretty comfortable believing they do not.

There are plenty of smart hardworking people with clearances. I believe in them and I believe they're generally trustworthy, but are held to an impossible standard so they can be fired at any time. I get it, but I can't accept that, so I don't.

Also the the OPM breach was cool.

For myself it's somewhat ethical, and somewhat practical: there's no way I'd get cleared anyway, due to my history of hard drug addiction in my teens and early 20s. Despite being sober for... gosh, over a decade now, it's a moot point in that process.

This comment gives a pretty good account of why myself and others are not interested:

https://news.ycombinator.com/item?id=20556201#20557382

Being subjected to pseudoscientific security theater isn't really that appealing.

Did you miss the several times on the news where whistleblowers had their lives destroyed after speaking up about literal knowingly bombing of children?