As for the origin of the expression, I immediately thought of being fitted for a suit, not cards (as mentioned in a comment below the question).
But, that aside, when you say that X is better suited for Y, it's normally meant to indicate that X is something better designed for Y (than anything else).
Gloves are better suited for hands.
It's ambiguous what the longer version of this could be:
Gloves are better suited for hands than feet.
Gloves are better suited for hands than are boots.
But, despite that, the thing that fits something is listed first, followed by the thing that is being fit.
In your example, you are trying to determine what format is the better fit for achieving customer success.
Therefore, I would say:
Structurally, the news format [gloves] is better suited to the customer success story [hands].