What's wrong with clutter in an advanced tab? The only clutter exposed to the "rest of the world" is a tab that says "advanced" which is not really clutter at all.
If you remove options from your product that are vitally important to even a small number of users your product can no longer "be used by anyone."
The problem here isn't that the unusual options exist in a hidden away tab. The problem is that the options to revert to the defaults are in the same hidden away tab.
Users with images turned off by someone else wouldn't be confused if there was a yellow stripe across the top of the screen with a "you're viewing this website with images turned off [turn images on]" type message. Same goes for a "this page may display better with javascript enabled. [turn javascript on] if you trust this site" message for those browsing with javascript turned off.
Similarly, as the original post points out, the big issue with SSL is that you get a scary (and inaccurate and incomplete) message telling them to email the website owners because their site is broken, and not a simple message they'll need to "click here to turn SSL secure access back on" to view the web page.
But for a user that legitimately wants to turn off images or javascript (why?), they won't want to see that message on every page. If the message only shows once then the problem the message was trying to avoid returns. If the message shows on every page legitimate users of the option are inconvenienced. Of course you could create yet another setting saying "Warn when I have obscure settings enabled"...
If the developers/designers of Firefox don't have a reasonably answer as to why a large enough amount of users would disable these settings, then they should be removed (or to avoid upsetting existing power user moved to about:config).
One problem is that browser vendors don't do a good job of sorting features into "Advanced" tabs and "important" options, so that some options that would be valuable to lots of people are buried alongside options that are valuable mostly to lab admins.
If I recall, there are some Chrome options that you can't modify from Chrome itself, but which you can configure using Group Policy Objects. That (or whatever the equivalent is on *nix--files in /etc?) should be where the settings for "lab admins" go.
Isn't the logical conclusion of this kind of reasoning that everyone should become a programmer and browsers should be supplied in source form only, so everyone can customise any tiny detail they want to? That's not exactly a realistic prospect for most non-geeks.
User interface development for mainstream software is invariably a balance between presenting something accessible to novice/occasional users and presenting something powerful to expert/frequent users. You can go a long way to helping both groups with a thoughtful design, but there's always going to be someone who wants something slightly (or completely) different.
For mainstream software, trying to please everyone all the time is a fool's game. That's what bespoke development is for.
But where do you draw the line? What constitutes an "advanced option" worthy of dedicated UI rather than a customised build? What proportion or minimum number of users have to find it valuable for the effort and lost simplicity to be justified? When there are too many advanced options to manage sensibly, do we move to "advanced", "really advanced" and "actually quite scary you even thought of this" options?
Love to know how numbers of users affected is measured. One of the arguments is that with a large enough number of users (millions) an option can cause significant numbers of people grief if they misuse it.
Same argument can be said for removing a feature 2% of the population of users rely on. 2% of 450 million users is 9 million users. Not what I'd call a tiny number of users.
If you remove options from your product that are vitally important to even a small number of users your product can no longer "be used by anyone."