Not having played the game, this prompted me to do image search for screen shots and art assets, and I can see it. He's speaking in hyperbole of course, but it does seem to languish a lot more on skin tight clothes and large breasts and needless pieces of skin flash. Most of what I see doesn't really look so much as outfits as they do your typical anime bodysuit/bathing suit/bikini armor. And looking back at Xenoblade 1, they definitely had noticeable cleavage and pieces of skin showing, but the things they wore looked like actual articles of clothing and outfits real people could/would actually wear
Have you played Divinity: Original Sin? An entire massive western RPG that may not have been designed specifically for co-op, but it was designed specifically to cater to co-op. And the sequel was designed specifically for co-op. And they both do an exemplary job