Yes, for mages you are correct. For moral heroes it defeats dodge. Hit rating does not increase damage in any shape or form. Each mage has a different base miss chance so some need high hit ratting as a priority such as shayd, and some such as mulan do not need it as a priority.
It should be noted that the dodge of the target will have a huge effect on the miss rate of mages. I actually did my labs for a month while on level 2 hard while my hero with the most magic defense did not use a dodge and he had about a 50% chance of finishing the lab as opposed to my other heroes having about a 98% chance the 2% variance was on times i hit the 50% reduction in health squares multiple times a hero or 2 with dodge would die.