All of what you just said, never stopped Disney or Nintendo from going after peeps for using their material.
Indeed. Apparently SR7 got some compliments for the quality of his artwork. This was before the current copypasta of course.
DC do seem to allow people a little more leeway regarding the parody defence - presumably their lawyers have a different viewpoint than Disney's or Nintendo's.
(I used to work for a corporate law firm - ask any two lawyers about an 'interesting' legal question, you'll get three or more viewpoints!)
It was the video game devs defending the title (from what I can ascertain). Since they do not own the character IPs they didn't enforce the IP. I suspect gunsmoke also got some advice about not incorporating the male superheros since DC is much more protective of those IPs and that income. That could have even been in the C&D letter they received.
Disney's war coffers are much larger than DCs thus they can pay and dedicate staff to rights protection. Plus they can use their weight to bully the companies adjacent to the offense. But with that said is there any Porn game devs that have received C&Ds from Disney? I'm not aware of any and there is several active porn games that Disney could point the Eye of Sauron at.
Nintendo being based in Japan is utilizing those IP law's which don't have much if any leeway for parody. Like Disney, Nintendo also has war coffers used for rights protection.
One other thing C&D letters are just notices of what some lawyer thinks. They don't have any binding legal judgement that goes with it. Part of the US IP rights law is showing that The rights holder is protecting their IP. So these letter can be used on bigger cases if some one claims the IP isnot being defended. So for most of these low level incursions these C&D are enough of a scare tactic to end the offense by the offender or those adjacent to it, like the domain host and storage provider. For example Akabur quickly changed Hermione Trainer to Witch Trainer after receiving a C&D from WB yet he went onto release the project and continued to use the character in SC34