Locked pages are not a concept exclusive to TV Tropes. Most large wikis possess this infrastructure to control pernicious editing. While the general wiki principle of "anyone can edit" usually works, it's a simple fact of life that most people are idiots and will eventually behave stupidly if given the chance. The locked page mechanism on TV Tropes works to protect pages from petty edit wars and untoward behavior by simply not allowing anyone in to edit the page.
Where TV Tropes differs from most wikis is the length of the page lock. Most wikis will unlock a page once enough time has passed for the involved parties to calm down. At TV Tropes, locks stay up indefinitely. This started out mainly because of indolence. Only administrators (to begin with, at least) have the ability to unlock pages, and given all the things an administrator has to do, it's easy to see how they could just forget to unlock pages, particularly since they could easily be at risk for petty sniping as soon as they're re-opened.
Over time, though, tropers from all over the wiki would run into random locked pages and were mystified as to why they were locked, since no explanations were ever given for these states of being by administration. Eventually this manifested into paranoia. As tropers increasingly saw problems of the wiki being a result of the nefarious actions of other tropers, it was a small leap for them to conclude that these same other tropers were such a danger to certain pages of the wiki, that the pages had to be locked up just to protect them from whatever damage such other tropers would perpetuate upon them.
I've been aware and accepted this attitude for almost as long as I've known about locked pages- it's an easy attitude to acknowledge. I started to question its validity when a discussion broke out on the page of Metroid: Other M shortly after its release when some tropers suggested locking the page to keep it from being wrecked by the Metroid: Other M hatedom, wherever they were- this page hadn't experienced significant damage yet. When other tropers objected to this, I found myself agreeing with them- locking a page should be a last, not first resort. Especially for a title like Other M, which was criticized mostly because of its perceived poor use of tropes.
The page was not locked, mostly because I don't think an admin ever saw the discussion- admins, after all, were the only ones who could change "locked" status. Consequently, when I returned in basic capacity to the forums, I realized I could try to alleviate some discussion page complaints of "why is this page locked" by taking the matter up in the forum. My first target was the Barack Obama page. Conventional wiki wisdom stated that political pages were just too dangerous to edit, but I had previously rewritten the Sarah Palin page in a way to make it more relevant to tropes, and indeed, the very fact that a non-vandalized Sarah Palin page existed to begin with seemed to prove that relevant pages about political figures could be created.
In Trope Repair Shop there was opposition to the page being unlocked for the same reasons already mentioned- a fear that political people would come to the page and somehow ruin the site. I attempted to dispute this on the grounds that there was no proof this would happen (see, again, the Sarah Palin page), but this went nowhere. Fast Eddie didn't seem especially convinced, either- until someone arguing against me actually made a statement, nearly explicitly, to the effect of "we can't give those nebulously defined other people a chance to ruin the site!" This statement was so extreme and counter to the wiki's "anyone can edit" principles that Fast Eddie unlocked the page right there.
Unlocking pages is surprisingly easy, all things considered. Even though only an admin can unlock pages, the nature of this authority can easily force some sort of decision to be made, because either the page is unlocked or it isn't, and the person who makes this decision can't be second-guessed because he kind of runs the wiki. Contrast this with consensus, which has an extremely vague authority and seems to be redefined to fit whatever discussion it happens to be brought up in.
Incidentally, Fast Eddie isn't the only person who can unlock pages- he's simply the only one likely to, because moderators with unlock abilities run the risk of offending him if they try to make a decision he disagrees with. Of course, I had to worry about that, too- I only made four or so unlock proposals, spread out over time and only made by direct request. I didn't want anyone to think that I was strongly challenging a core wiki idea, even if it was an idea as unsavory as paranoia against fellow tropers. Such challenges to operating procedure were indeed dangerous, as I was soon to find out firsthand.