When the hosodapocalypse comes, I'm joining team Cajun, inasmuch as that means cat ears and tails on mostly human ladies.
Not sure if I'm ready to embrace the full on Bagi world.
Well, putting aside Bagi not really being drawn with that pleasant an art style to begin with, what about a Miiya Miiya world?
I'm totally fine with calling it a contrived situation and understand being angry, sad or whatever...but contrived events in general aren't a rarity in anime, much less in this show. Looking at the big picture, resorting to tragicomedy isn't unfitting for what the creators were already doing in the series nor what they did afterwards. The series wasn't ever meant to be as serious as the Legend of Galactic Heroes or even most Universal Century Gundam works. The tone's too different.
Let's not look at what happened in isolation, because then you'd be missing the forest for the trees. As you say, simply having a modest amount of contrivance isn't a deadly sin, but when your show writes itself into a corner so obviously, and then fully entrenches itself in there, it calls attention to the use of a megaton contrivance warhead to blast out even more than it would otherwise! It would actually be MORE acceptable to portray Lelouch waking up and realizing the past 5 episodes were all a dream, so WHOOPS NEVERMIND LET'S DO THIS OVER! The decision they made was the equivalent of splashing paint everywhere to turn a Bob Ross landscape into abstract statement on the color red because you realized you were painting palm trees on a snow-capped mountain.
Also, the "never meant to be as serious" claim is entirely disingenuous as it started out taking its own premise seriously. Sure, it had the usual anime trappings, but everything was fairly legit until then. It's only once THAT happened, and then pretty much all of R2 could you even have evidence to the contrary. Quite clearly, the show veered off course.
To me, that only seems useful as trivia to satisfy a sub-set of the viewers who wished to learn about it, but not very relevant for the story being told. The evolution of magical eyes in an over-the-top show isn't some sort of scientific phenomena that needs to be repeatedly observable in a controlled environment to draw forth a peer-reviewed conclusion. Maybe it's happened exactly this way before, maybe it hasn't. There's no point of contradiction. The series isn't about Lelouch's or Suzaku's fervent desire to understand all things Geass and use science to counter it, though that would have been cool to see.
Well, that's the post-modernist take, but suspension of disbelief takes a massive hit when you start giving new powers to character like a 5 year old with an action figure. Sure, there's no point of contradiction, but at that point who really cares?