I've read most of your comments in this thread and the analogies and conclusions are all flawed.
1) A desert eagle is a poor home defense solution. I have locked doors, soon-to-be camera feeds with secure offline storage, and a 9mm. Defense in depth.
2) Under most circumstances, it is absolutely criminal to open my unlocked front door if I have not invited you in.
3) Passwords and usernames are for Identity and Access. In fact, the term "IAM" for Identity and Access Management is common in IT organizations. The AAA protocol for network Authorization, Authentication and Accounting exists to make sure people are who they say they are, only go where they're allowed to go, and that such accesses are properly logged.
You act as if we shouldn't even be trying to be secure in our online accounts... or are you? You then go on about how important it is that no one break your twit account.
The only part of your discussion that approaches coherence is the concept of "reasonable" security. Yes, no security is absolute; all security considerations in all facets of life are about likelihood and risk of a danger, cost, and mitigation. Sure, if someone is writing some ad-hoc utility that has minimal operational impact and no personal data, cleartext passwords probably wouldn't be a risk in itself. Its the fact that salting and hashing with proper algorithms takes almost no effort, and provides benefits, and is a universal best practice out of habit. If this technology advances to the point of being easy to deploy and easy to maintain with minimal effort, it could and should become perhaps the next password storage best practice.