I was looking up stuff in the wowwiki Weapon Skill
It's an old wiki article but ...

"Let's say you increase your weapon skill by 4.
Against a mob 3 levels higher than you, you get: 0.8% lower chance to miss,
0.4% lower chance to get dodged, 2.4% to be parried, and a 0.8% higher
chance to crit."


So I guess it comes down to weapon skill does affect hit rating, at least for melee classes and you can get +weapon skill items.
I don't think spell casters are affected by weapon skills in the same way.
I just feel that it's not equal at the lower levels... my melee classes at lower levels do better than my spell casters. melee keeps fighting even it it's OOM.
A good example is Hunters auto-fire their bows/guns after a spell cast while a spell caster has to manually switch to a wand.