Nah. Regardless of how I feel about diamondback I would not have wanted Cottonmouth to be the antagonist for the whole show. He really wasn't even a little bit of a threat to Cage, and he was always on the defensive. A good character but I don't see him being a compelling antagonist for a full series.
Captain America Civil War: Tragedian Structure

Why they killed Cottonmouth I do not know.
Being that they did they should have went hard with Mariah Dillard and Shades.
I was okay with Diamondback but it required I totally reset my mind.
The same thing happen to me the second half of Daredevil season 2.
They seem to be trying to satisfy adults the first half and kids the second.

This is the only thing I didn't like about the show, but I don't think Luke's enemies are in it for the long run, they're just there for filler, like the whole Luke Cage series, it's just there to introduce us properly before bringing them all together for an Avengers tribute gang for Netflix.

Cottonmouth seemed out of his depth and bad at being a gangster - kinda like Vince Vaughn in True Detective season 2. Diamondback seemed way more intimidating and competent - I just think his motivation was childish and lame.
I never saved anything for the swim back.

Agreed. Diamondback was a boring villain and was on far too many episodes.
Cottonmouth was a much better villain.