The reason I'm including them is because they really are an odd cultural relic. When I first started looking at them, I noticed they had a western theme, from the Maverick font, to the horse on the Joker, to the stylized Ace.
That's because Mavericks almost certainly entered the market as a tie-in (either official or unofficial) to the James Garner TV show of the same name. Since Bret Maverick was a card sharp, cards featured heavily in the show, so it was natural tie-in.
The show began in 1957 and went off the air in 1962, which means that this is a pop culture artifact that survived 48 years longer than the show it was based upon. I just think that's cool.
Brand loyalty is the reason decks like Aviator and Maverick remain in print. As a company representative told me, "Each brand we manufacture has a deep history and avid followers. People remember playing with specific brands growing up and want to continue that tradition."