Why didn't Kirino play Big Brother otome games?
Because she has taste.
Because fat otakus wouldn't be able to self-insert as easily.
The whole point of the series was "LOOK LOOK SEE?! ITS TOTALLY NOT A DISGUSTING HOBBY! HOT GIRLS DO IT TOO"
That wasn't the point at all. The first 5 episodes maybe, but it pretty much never came up again after then.
Because the exact genre isn't what's indicative of what she wants.
Because she was in denial.
I guess you can call it overcompensation. She wanted to give the little sisters the love that she was unconsciously wishing for.