While I agree that having a super detailed UA string sent isn't in the best interest of my privacy, there is a sort of "tragedy of the commons" problem if everyone did that. If website maintainers/webmasters/web developers didn't collect that data, they wouldn't know what platforms to optimize and account for when designing. (Yes, best practices dictate that a website should work well on all platforms, but best practices aren't always followed.)

JS disabled by default - seriously? So many apps nowadays rely on it and are JS-driven. I can't imagine how that would be a better experience, regardless of what you think of the language.

Can you please elaborate more on that one in particular and why you'd want it?