They arent any more useful than pirates for the sake of Edwards treasure generation, and while a few creatures have both types (mostly other Black Flag characters), adding most assassins to our deck is just diluting the pirate synergies and vice versa
It turns out that some cards appear on their surface to be very simple, but once you understand more about how to use them, they become more complex
Modern sets like Surging Sparks illustrate unwavering support for Pikachu, but Raichu has never been able to replicate its pre-evolution's success as the series mascot
The row's are designed to be wider, to fit all graders, even loose cards
In this case, it seems that WotC thinks that these mechanics are RELATIVELY similar in value when placed on a creature, which again makes a lot of sense