Is not the first time the author write such character, just read/watch Oreimo.
(please forgive this text wall of a post, this is something I've been thinking about all day already and using this as an excuse to talk about it. I was going to type something like this up anyway, you just helped me bring it up.)
I was thinking about this myself, but I don't quite agree. On the surface Kirino and Mei seem comparable -- coming from a place of the author idealizing a loud, ungrateful and self-centered girl. I do think both probably appeal to the author for similar reasons. A major difference is that Kirino never manipulates or
forces Kyousuke to wrap his whole life around her. He does it pretty much all of his own volition and arguably going way too far with it. Even Kirino is a bit weirded out by it. In the end, the repeated sabotage to Kyousuke's personal life over Kirino comes about by Kyousuke's own will. Similar circumstance vis-a-vis Chiaki and Mei certainly, but it's the difference between being stabbed by someone and impaling
yourself on a spike from a running start.
Regarding Kirino, the otaku culture aspect of Japan of 2010 really is remarkably nothing like it is today. Back in the 00's and 10's it was a lot more straight-laced, sex-negative, anti-LGBT and intense internal sensitivity about Japan's perceived outside image to western (especially American) societies. Kirino having deviant interests and being clearly non-straight despite having to maintain the reputation of a first class student... yeah, immense pressure on a teenager. She's intensely vulnerable and endangered in a time where just being herself would've been social suicide. Her fears of rejection pretty much proven when Ayase, her best friend, turns out completely hostile and disgusted by the small glimpse she gets of the "true" Kirino. In light of the social dangers she's in, her effective isolation and just being an immature teenager in general I find myself inclined to forgive Kirino's selfishness.
I think Oreimo actually did a good job of helping put to light Kirino's plight and it was part of a culture shift away from that self-censoring, otaku-loathing puritanism. I think the transformation really hit its full speed around 2017. That's when NieR: Automata came out and was well received in both Japan and the west despite Yoko Taro's team not making any attempt to self-censor. That's also the year vtubers begin to make their first appearances and... well... the rest is history. Shameless vtubers have done a lot to be a blazing beacon of comfort in a world that's been feeling increasingly dark even to this day. But I digress.
tl;dr -- Kirino deserves a gentle flick on the forehead. Mei deserves to be thrown down a flight of concrete stairs during a thunderstorm.
