Perhaps the most important contribution of professors doing research is that it creates (or at least enforces) lifelong learners, learning that involves making mistakes while pursuing the joy of discovery.
America has always had a pioneering spirit, and we have always admired pioneers. They may not wear buckskin anymore or climb into space capsules. They just may be the quiet person in the lab of a research university, studying particles too small to be seen.
With $250 billion in endowment and a group of the most accomplished individuals on the planet, research universities have no choice but to gear up to attack the world's biggest problems and provide a jump start to getting the pie growing.
Research universities' problem is not that they have many functions, it's that they engage in false and misleading accounting practices that result in escalating costs and decreased educational quality.
Ironically, many of the budgetary forces at universities work to drive up tuition costs and lower educational quality; and most of the reasons for this strange combination have to do with compensation.