All three have since rebooted into “fresh” territory, to varying degrees of success (75%, 84%, 73%), but the descent back into “rotten” was inevitable (56%, 28%, 52%). Batman has since recovered again by going on a vastly different direction with Joker (if you think Baby Bruce’s appearance qualifies it as a Batman movie), while Spider-Man freshened up by joining the MCU.
Speaking of which, Marvel Studios movies never sink too low on the Tomatometer, but even they clearly alternate between the ones that are truly beloved and the ones nobody ever watches outside of marathons (and they’re mostly used for sleep/poop breaks). Oh, and note that among the individual series, all of the lowest-scoring movies are Part Twos: Age Of Ultron (75%), Iron Man 2 (73%), Thor: The Dark World (66%), and The Incredible Hulk: Fuck You Ang Lee But Also Thank You For Telling The Origin So We Don’t Have To (67%).
To understand why superhero movies seem to bounce between awesomeness and mediocrity, we have to go back to the comics. Let’s return to the X-Men, since the good/suck cycle seems to be embedded into their DNA. (It’s their unspoken common mutant power.) The comic debuted in the ’60s in the hands of Stan Lee and Jack Kirby, who introduced the concepts of mutants, mutant supremacists, the Xavier School for Gifted Youngsters, the Danger Room, and Professor X being a creep, all in the first issue.