I think the emphasis is supposed to be on the ‘should’. That is, it’s not in the user’s rational interests to run such software. Hence the locked down security model all the platforms are moving toward.
You’re assuming all Debian packages are secure. Like wlesieutre said in a sibling comment, software from a trusted source can and often does have vulnerabilities.
A design that dooms even savvy users to being compromised is simply not acceptable anymore. Most people are not discriminating enough about the software they install. But okay, maybe you actually are and never make mistakes[1]. But is all the software you use signed? By a certificate traceable to a real, accountable person? Can a software update, perhaps released by someone who has hacked the original developer, come along and turn it into malware? Because all of your apps have full-capabilities, it can now do things that you would never grant if explicitly asked.
Now you're completely screwed. All of your emails, pictures, medical information, other embarrassing personal information/media, bank logins, and so forth are compromised. Maybe you have two-factor authentication for all of your accounts (doubtful), but who cares? It can just read the memory of your browser process, quietly wait for you to login to the various services, and then hijack your sessions in the background.
So tell me: how in the world is this an acceptable situation?
[1] I sure hope you never use any of these new-school package managers for various programming languages, text editors, and such. You know, the ones that grab the latest commit from GitHub repositories run by total strangers and then run them with full privileges.
We built a great western civilization largely on the basis of ideology. Chief among them, natural rights. The most beautiful and famous declaration of this ideology is in the Declaration of Independence: "We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the pursuit of Happiness. [...] But when a long train of abuses and usurpations, pursuing invariably the same Object evinces a design to reduce them under absolute Despotism, it is their right, it is their duty, to throw off such Government, and to provide new Guards for their future security."
This itself is an evolution and addition to much older Christian ideas about human dignity, care for the poor, love of fellow man, and duty to do good.
>By discussing these issues and being open-minded, pragmatic, and rational, and by evaluating them on a cost/benefit basis.
And that's exactly what I'm doing. It sounds like you just want to discount all of the arguments of one side for being 'ideological'. That's a specious argument. Freedom is as much a good as environmental cleanliness and the lack of congestion. Why should it be excluded from your cost/benefit analysis?
Social engineering, environmental causes, and freedom are exactly what this is about (as well as congestion, which I forgot to mention earlier). How should decisions about a society be made? If public transit is a social good, is it okay to encourage it by taxing people out of their cars? Even though people clearly prefer their cars for all of these reasons? What if city planners fail to foresee a technological innovation (like fleets of self-driving cars) and end up spending billions and inconveniencing millions over an ultimately unnecessary cause?
Let's use another issue for example. If we wanted to end Cosa Nostra (the capital-M Mafia), and didn't care about freedom, the cops could tomorrow round up all of the known members and throw them in jail forever. Or better yet, execute them. That would end the whole ordeal. We don't do that because we think there's a greater good in freedom from arbitrary arrest and detention. We believe in due process and the rule of law. There's in fact good logical arguments underpinning and supporting the utility of these ideas, but we don't need to trot them out every time we invoke the ideas themselves. They are cornerstones of our very successful civilization.
I live in a city with great public transit. I take the bus to work (~15 miles) every day. I don't have a car because it's expensive (car payment + maintenance + parking) and I can't justify the expense.
But cost aside, I'd much rather have a car. With a car, you go where you want when you want. No bus schedule to plan around, no multiple connections. You can play whatever music you want at whatever volume. You can easily transport items larger than a backpack. You don't have to sit next to a smelly or rude stranger. Much to the chagrin of social-engineering city-planner types, Americans value their freedom more than they care about some environmental cause. And let's face it, public transportation will not solve America's gas consumption and pollution problems. Most people live in sprawling suburbs that can never be adequately served by public transportation.