Abilities like Bloodthirst do auto target, it's been default for a fair while now. I literally did it before hitting post on that comment to confirm it, too.
Originally Posted by Daerion
If you desperately need something for Charge then just use /targetenemy in the macro, e.g.:
E: You can remove the intercept part, that's because my alt is Prot.
/cast [@mouseover,exists,help,nodead] Intercept; Intercept
/cast [harm,exists,nodead] Charge