It isn't that simple. One of the key reasons for the tenure system is to insulate "thinkers" from political or social pressure. Tenure allows researchers to be more objective because they don't have to worry (as much) about being fired for unpopular teaching or research findings.

This system has already been polluted by the prevalence of corporate funding for research, but destroying it entirely would be a terrible thing for society as a whole. There is certainly waste (and we should try to minimize it), but some waste is worth the benefits in my mind.