I'd say because teaching has a higher payoff for the students being taught. They can get jobs immediately after college and contribute... Research on the other

I'd say because teaching has a higher payoff for the students being taught. They can get jobs immediately after college and contribute... Research on the other hand, outside of the self-serving aspect - like how many papers one gets published - has hardly any immediate benefits relative to the benefits of teaching... and few long term benefits. It's more of a gamble.