By now, as a member of this community, you'll know that the comma is not a state of being and a semicolon is not a surgical procedure.
And here is a prime example what the misuse of a comma can do (credit goes to southernwitch69):
"I want to come inside Harry!" Ron shouted.
You can't help but scratch your head if this is in a fic that has absolutely no slashy tendency, right?
"I want to come inside, Harry!" Ron shouted.
Doesn't that comma just clarify what Ron said?
In dialogue, ALWAYS separate the direct address with comma(s).