Too sick to be eloquent, so forgive if I jumble this a bit."Nodoka doesn't have common sense" Ok, but she should have logic? Like you can be completely detached from the situation and still see how it puts Futaba at risk objectively. Like either she's smart or she's retarded, you can't just conveniently give her 0 IQ when the story needs her to be like that.
Nodoka isn't written like a smart character, she's written like a caricature of one. The callous, detached, possibly even sociopathic behavior, and general smugness that makes you want to punch her. No focus on any area of study so she just knows everything about everything and reads people like books despite her abject lack of social understanding.
She basically comes of as a character written to be how DeGrasse views himself, and the modern views and associations of morals being dumb and nihilism being a sign of intelligence.
If it's not intentional and she's not actually supernatural, she's a poorly written character, and even then she kind of is.
A general rule, a writer can make a character far smarter than themselves, but they can't really make a character wiser than themselves. Not intentionally, anyways.
Sel isn't STUPID, but he certainly isn't a wise man as we've often seen from his childish, egotistical behavior, and while his writing has plenty of smart points to it, the attempts to be mysterious and deep often dip into pure pretention.
Nodoka, when she really gets going on her views and motives, is the pure embodiment of this.