I think people need to be very careful when they offhandedly dismiss something as being irrelevant or useless. To be a successful scientist requires one to develop a unique perspective that gives them an advantage when looking at certain problems. Most people are very specialized these days, but there are certain people (I can think of several physicists) who are able to make significant contributions in several different areas. They are able to do this because they have a wide base of knowledge and are able to use it to think of new creative ways to approach problems that never occurred to anyone else. For example, people have recently found connections between gravity and several different areas, which many people would first assume make no sense as they appear entirely unrelated. But actually there are very beautiful and intuitive arguments why this should be the case in many instances.