He came off as vindictive and a bit of punk many times.

Yes...
b/w episodes with a kid, Trey, and another with Andy's girlfriend, Peggy.

color episode with that brat who rigged Goober's dog to "talk"--he went right along with that.

Kind of. He grew up without a mother, you have to excuse him.

I still don't get why they never talked about that.

I like Ronny Howard and the Opie character, but scenes centered around Opie aren't in my many tags favorites. I dont think Ronny Howard had comedic talent where you'd fall off your chair laughing. Cute scenes maybe. I think when Opie got older using him as a ploy to irritate andy and Barney was funny. When Opie spilled the beans about the Taylor house flaws in Barney the realtor was good. Telling Andy not to waste food in dinner at eight. Spilling the beans in the auto show that goober only owned 1 station. He contributed to a few funny scenes. Though, I think Andy having a child gave the writers ideas to put Andy in funny situations. There'd be no delightful Helen crump too. Opie had some Value to the show but way down the list.

The only time I remember Opie being a punk was in the first couple of episodes in Season One. Ronny's dad Rance Howard put a stop to it, pointing out that such behavior wouldn't be cute forever.

One thing that always irritated me about the later Black and White seasons was how they turned Opie into such a poor student for the sake of shoehorning in Helen Crump. This wasn't just limited to TAGS episodes as on Gomer Pyle USMC he appeared after running away from home due to getting all Fs on his report card. It really got to the point where you wondered if Opie needed academic help give how bad he was doing.