Malazaar

The benefit of hit/expertise is better modelled by looking at the bad things that missing/dodging do:

1. Missing Autoattacks do no damage.
2. Missing Finishers do no damage and refund no energy.
3. Missing Specials (Mangle, Shred) do no damage but refund ~82% energy.
4. Missing a Mangle after applying Rip will cause your first rip tick to do 30% less damage.
5. Missing a Clearcast-Special does no damage and does not refund energy either.
6. Missing will reduce your 2t4 and Clearcast proc rates accordingly.
7. Having a particularly bad missing streak may cause your energy pool to 'overload' or completely throw you out of your cycle.
8. Missing repeatedly will cause gcd issues.

I believe only 1-3 are covered in the common dps calculators, so the real value of hit is a bit higher than those are telling you. Though the impact of points 4-8 are not that big, they should be considered nonetheless.

Expertise is of slightly more value than hit because you will also have to deal with parry in some encounters (gorefiend for example will turn quite frequently). Expertise has twice the value of hit in scenarios with parry (mainly while tanking).

Keep in mind that expertise is not only more TPS and reliability for a tank, it will also slightly reduce incoming damage due to less parries.