I think people who are too in love with their own rationality leave themselves vulnerable to some pretty ridiculous beliefs that common sense would normally guard them against. A suspension of common sense is certainly important sometimes, because common sense can lead you astray, but at other times it will save you a lot of time and mental energy. A classic example from antiquity is Zeno's paradoxes of motion. It was not immediately clear to people trying to rationalize about these 'paradoxes' how they could be resolved. But somebody who is slightly less in love with their own rationality, who trusts their own common sense, would not waste their time wondering about a supposed paradox that can be refuted by standing up and walking around the room. Failing to balance rationalism with common sense can get you stuck in solipsist traps or worse.