I watched Rebellion
probably about a month ago now. It was a good watch at first, with laudable aesthetics and a sense of intrigue that seemed like it was building up to something interesting. That something, of course, turned out to be even more "lol anime" than the show's ending, by light-years. I would have been satisfied enough with Madoka taking Homura away and leaving the others behind in the experiment's dusky ruins. Instead, "HURRR DURRR, BECAUSE LOVE IS DESTRUCTIVE I'M SUDDENLY THE DEVIL AND MORE POWERFUL THAN GOD! ENJOY MY RETOOLED REALITY AND A POINTLESS AND SUPER-DERIVATIVE RESET ENDING, SUCKERS!".
The stupid was so overwhelming that an otherwise positive anime experience was soured. I made a token attempt to revisit the series and maybe see if Movie 3 actually could make sense, as some have claimed, but quickly dropped the idea and moved on to other things. The mechanics of the Madoka
universe are simply not interesting enough to me to warrant the effort.
Arguably there are two main reasons behind Homura stealing Madoka back and resetting the world at the end.
First, there's the practical reason: the entire setup of the movie hinges on the Incubators having created an isolation chamber where they'd be able to observe the Law of Cycles (i.e. Madoka) to be able to understand and control it. If Homura lets Madoka take her away to Magical Girl Heaven, the Incubators win. They've seen the Law of Cycles in action, and they then expect to be able to control it and return to the original system, thus nullifying Madoka's wish.
The second reason (and this might be more theoretical on my part) is that Homura is continuing to act out her wish, which was "to protect Madoka". In the series, her wish meant that she would have to continue protecting Madoka, with no possible respite, even if she had wanted to give up, because the aftereffects of trying to protect her made the threat grow larger and larger. Magical girls aren't just bound to a life of fighting, they're also bound to the wish they made and whatever comes of it. Homura wants to save Madoka from herself, from her self-sacrificing nature that led her to become the Law of Cycles. Countless timelines after she made her wish and her promise, Madoka has changed due to her well-meaning interference, but she's still trying desperately to save the original Madoka who no longer exists.
Homura becomes a demon not because love is bad and makes you a bad person. It's because she
hates herself, and sees herself in that light. From an outsider's perspective, she's finally managed to save all of her friends from their fates, Madoka included, and gave them a happier ending than they got the first time around. But she's not the same person she was before, she's basically given up on trying yet again to get close with her former friends, and she's carrying around the weight of countless timelines' worth of failures and all the self-loathing and guilt that comes with it.
Plus, the series' ending really didn't wrap up the main story. Madoka is the title character, because the show is crafty like that, but throughout everything it's really Homura's story, and her story didn't get a proper resolution in the series.