What the "theory is worthless" means is that practicality and effect is more important than "discovery". Sure, people can talk about "string theory" all the want. Unless they are doing it for the betterment of mankind (in a way similar to cancer research, trying to grow more crops, communication, etc) then there is little point to it.

Descartes made it clear that the material world is only important insofar as a man can use it to better mankind. I guess you could consider this a humanitarian approach to science.