That humans are actually the rational beings many claim themselves to be, rather than animals that makes decisions based on emotion and then rationalise why they made the decision.
I feel it would solve all the problems other commenters have mentioned.
While I agree there are some problems that would be best solved through rational thinking, I wouldn't want to live in a purely "rational" world. The entirety of the human experience lies between the gaps of rationality.
Wanting to feel love and happiness is quite rational too. Irrational feelings are not “anti- rational” they are just orthogonal, like color to taste. But making decisions based pure on feelings IS anti-rational.
That's a popular trope that is spouted by anti-rationalists all the time, but it's a total red herring. It's one of those rhetorical tactics that is designed to disrupt judgment and put a stop to a conversation before the absurdity of the claim is made obvious. It's drilled into us as children through tv, movies, even books, but it's entirely false.
Rationalism has plenty of room for fantasy, emotion, and everything else that humans experience. It's not a choice between being rational and being a fully developed human. The choice is between being rational and being irrational. Everything else is its own separate thing.