On a more contemporary front, common political and pluralistic decisions are taken by people on temporal moral high ground and emotionally charged planes, resulting in win of short-term goal seekers. After all, being intelligent is no easy task. One has to continuously abreast oneself of new knowledge and information, analyze existing information in light of new one, apply principles of logic and reach a informed decision, and accept possibility of unclear answer in light of multiple views and insufficient information. This entails very precious time which can be utilized breeding. Similar behaviour is observed and documented by political scientists and is termed as "rational ignorance" of voter. What it means is that for each voter cost (of time and money) to obtain information to objectively evaluate each candidate is very high. On the other hand chance that his/her vote will be deciding vote in election is very low. So, rationally speaking, it is best for each voter to not bother about finding who is right candidate since others will anyone choose one. However, when each voter thinks this way, overall outcome is failure of system.
Hence, stupidity (lack of objective logically backed opinion for issues immaterial to immediate surrounding) is desirable for short-term life goals for an individual but undesirable for long-term goals of a society. And as Charles Darwin has said (for genes, but also applicable here), individual selfishness is usually winner against collective collaboration.