Cohen v. Pesic

Kepler is apparently one of the most polarizing figures in science. Pesic seems to truly appreciate Kepler's methods, and gives him a lot of credit for his unusual way to the truth.  It doesn't seem to bother Pesic that Kepler stumbled upon things and made errors that cancelled out.  

Cohen, on the other hand, seems like a Kepler hater.  He says that "Kepler was a tortured mystic, who stumbled onto his great discoveries in a weird groping." He blatantly says that Kepler could never be mentioned among Galileo or Newton because their methods and "purposeful quests for the truth" could never be described in the terms used to describe Kepler's methods.

Is it important in the sciences to come about things because of "purposeful quests" or is "weird groping" all right for discoveries?