Perhaps the position for which I have generated the most flack on maintankadin is my support of hit rating for protection paladins. Along with one or two other people, I am one of the biggest proponents of hit rating for a protection paladin, and I have raised much ire for holding this position. The topic is very interesting, as it covers a number of buried disputes about the nature of tanking.
Hit rating for paladin tanks is our second best threat stat, after strength. It also has no mitigation value of any kind. It is useful, however, for two things: burst threat and pickups.
Every skill we have except Seal of Vengeance uses hit (including Consecration, oddly enough). On average, strength gives me more threat, and over time, it will give me more threat. However, the reliability of how much threat I can build up right away is affected by hit rating more than any other statistic. A whiff or two early on in the fight creates the real possibility of losing aggro to an impatient dps who gets off a lucky crit or two. This happens more often than we generally are willing to admit, and it is usually perceived as the dps's fault (which it is). However, if I can prevent a wipe, who cares whose fault the wipe would have been?
Both of our taunts, Righteous Defense and Hand of Reckoning, as well as both of our ranged pick-up skills, Exorcism and Avenger's Shield, rely on hit rating. I am constantly picking up adds throughout a fight and there are a number of fights, like Razorscale or Hodir, that depend on perfect taunts. Other fights, like Auriaya, require me to threat adds with nasty damage increasing bonuses out of packs. In fact, the only fight in Ulduar I have seen that doesn't require me to pick up something or taunt something is Flame Leviathan.
The arguments against hit rating tend to come in three sorts: it isn't our job, it's just opinion and it's useless. All of these are interesting, because they aren't really about +hit rating directly, but reflect deeper disagreements about tanking as a whole.
"It isn't our Job":
This argument is summed up with something like: "It isn't our job. Our job is to maximize survivability and threat. Hit is worse at both than other comparable stats. Therefore, it is a bad stat"
The problem with this argument is that it makes some very odd assumptions about what our "job" is. The general mindset here is that what a "tank" does is stand perfectly still and tank big bad meanies using an ideal threat rotation. This is true for some fights, but for most fights it isn't true at all. Even main tanks need to share bosses through taunting (there are a few fights like this in Ulduar, like Hodir, Razorscale and Thorim, just off the top of my head). Maximizing average threat is also misplaced. It is only relevant in cases where we are threat capped, which are few and far between. Threat capping hasn't been an issue since 3.0, so trying to maximize threat is like trying to maximize overhealing.
Our "job" is whatever job we have in a given fight, which may even include things like dpsing when we aren't tanking (like of Deconstructor) and, usually, includes picking stuff up and saving the squishies. There is no "real" job for us.
"It's just opinion":
This argument is the result of a really simplistic epistemology that is all over internet forums: if it isn't measurable, it's just opinion. There's certainly some utility to this view for settling and focusing disputes, but it's simplistic, self-refuting and misleading for a number of reasons. It's simplistic, because when taken literally, it would mean that statements like, "Bill Clinton was president of the United States" is opinion. It's self-refuting, because the view that only measurable things are facts and everything else is mere opinion is, by its own criteria, mere opinion.
I'm most interested though in how it is misleading, especially in the context of tanking. "Measurable" doesn't mean "easily measurable" or "measured". EH, "time to live", threat and avoidance are easily measurable. There is a certain comfort to sticking with the "facts". However, dead squishies, wipes from resisted taunts and overenthusiastic hunters are also measurable, they are just not easily measurable, nor has anyone developed a program to measure them. I'm sure, actually, that some of the world's top guilds keep track of exactly this sort of thing, though they have probably not collated any of their data.
Even if one accepted that because the benefits of hit rating have not been measured, they are just opinion, one cannot therefore conclude that it is worthless. If the belief that hit rating is useful for tanking is just opinion, so is the belief that it is worthless. There is no default practical conclusion in the face of a lack of evidence: if I believe that a chest might have gold in it, I open it; if I believe it might be boobie-trapped, I don't. Our practical judgements are a constant juggling and guessing in the face of lack of evidence. However, pretending that because something's value has not been accurately weighed it is therefore worthless represents some serious confusion about the conclusions one can draw from the fact-opinion distinction (even if one were to accept it).
"It doesn't work":
This is the view I take most seriously and the reason why, though I have quite a bit of hit on my gear, I haven't gone out of my way to be threat capped. The argument works something like this: "There's no circimstances in which I really need hit rating, even for snap aggro. I don't lose aggro when tanking, even early on, and I have backup taunts when I need them".
I do take this view very seriously, but I think it is mistaken in the end. There are two parts for it, the snap aggro part and the pickup parts. For the snap aggro part, I will note that it can and does happen that impatient and "lucky"-critting dps pull something right at the beginning of a fight. It is usually a hunter, but I've seen mages do it. I have a tendency myself to not worry about something because it isn't my fault. However, when I started paying more attention, I noticed this was definitely happening.
The second part is the backup view. This is true in some contexts, and since both Hand of Reckoning and Righteous Defense are not on the global cooldown, they can be considered true backups when they are useable. However, since Naxxramas, almost all bosses are now tauntable. This means Righteous Defense is just too dangerous to use in a number of fights, including Auriaya, for example. It why they gave us Hand of Reckoning in the first place. Second, in a fight like Thorim, I am using both of these taunts every time they come off the GCD. I don't have "extra" taunts to waste on misses. Exorcism and Avenger's Shield aren't really backups, either, since they may not actually pick up aggro and they are on the GCD.
So, I believe in both cases where hit rating is said not to really be useful, it is.
All in all, then, there's really a lot of content to the debate about hit rating, including some rather deep issues about the nature of tanking and even of knowledge. I've presented here the most comprehensive explanation I've done of my position. I hope you've enjoyed.