How +hit can affect your chance to crit in a single-roll system

+Hit does affect Crit in the single roll system. You can have 50% chance to crit, but if the total block + dodge + parry + miss chance on your attack table versus a given mob is 55%, then 5% of your crit chance is wasted.

Fun Fact: I also play a level 80 Fury warrior.

Consider the following completely imaginary attack table for a dual-wielding L80 warrior fighting a raid boss, with 50% crit chance and 0 expertise or hit. Assume the target mob is wearing a shield and has a 12.5% chance to parry and a 6.5% chance to dodge.

Hit:     n/a
Crit:    01-36
Block:   36-55
Dodge:   56-62
Parry:   62-73
Miss:    73-100

The warrior will damage the enemy 36% of the time he attempts to attack it, and 100% of that damage will be from crits. 14% of his chance to crit is completely and utterly wasted.
Crit fills up your chance to hit, but does not itself push block, dodge, miss or parry off of your attack table. So, without adequate +hit and expertise, your crit chance can actually suffer.

Let me repeat that: in a single roll combat system, you need +expertise and +hit in order to maximize your chance to crit. A 4 cup can of whoop-ass can't fit into a 2 cup Mug O'Hurt.

Now, let's put this into perspective for bear tanks. We automatically hit much more often than a dual wielding melee class would. We don't dual wield, so spare ourselves an additional +19% chance to miss. Awesome. We also talent into our first 10 expertise rating. Expertise pushes both parry and dodge off of the attack table, so is twice as valuable for threat generation (per 1% of effect) as hit rating, up until we hit the "soft cap" for expertise and completely push the 6.5% dodge chance off of our attack table. After that, expertise is exactly as valuable as +hit in terms of increasing the size of our crit envelope. However, it's still more valuable for tanks than hit, because it also improves our Effective Health.

Expertise contributes to our effective health? Yes.

Reaching the hard-cap for expertise so that your attacks can also not be parried by raid bosses is important for a tank, because when a mob parries a frontal melee attack, it gets a speed buff, reducing the time to its next white damage attack.

This is sometimes called the "Tank Jib". Think of it like a backdoor crit.

Even if you never suffer a critical strike, this speed buff can give the mob a big DPS increase and tax your healer, particularly if the mob is the slow swinging, big damage type. This is also a major reason why your melee DPS should never ever ever stand shoulder to shoulder with you unless they are hard-capped for expertise, meaning none of their attacks on raid bosses can be dodged or parried. They should stand behind the mob, because attacks from behind cannot be parried.

The bottom line for feral tanks is this: If you haven't pushed parries completely off of your attack table, you can benefit from more expertise. Unless 100% of your white damage attacks are critical strikes, and you are hard-capped for expertise, you don't need more +hit. Hitting hard cap on expertise will help your threat generation and, especially in 3.1 (if Savage Defense goes live), will also contribute to your mitigation. If you overemphasize crit and ignore the rest of your attack table, you can undermine your threat generation and survivability. In 3.1, if you overemphasize the rest of your attack table and ignore crit, you do the same.