After playing the beta and watching countless videos on ESO, it dawned on me that all the characters are right-handed. Was this a major oversight for Zenimax and should players be able to create left-handed characters?

No mmo to date has specifically created models and animations for left handed characters.

So I wouldn't exactly call it a "major oversight"

I don't..understand. Forgive me.

The OP is trying to imply that ZOS has made a "major oversight" by overlooking the "importance" that players attached towards been able to create left-handed characters.

The matter is of minimal importance.