It is so hard to compare drivers especially in different era's. Obviously Marc has been on an incredible run and I have yet had the opportunity to see him drive unfortunately but it is hard to imagine someone being rated higher than Masami Hirosaka and Joel Johnson. These guys dominated for decades! How many World Championships has Masami won? More than I care to admit
With respect to Marc taking out Hara. Again, I obviously was not there but from what I understand...he stopped and waited for Hara after the crash. If his motives were purely selfish "to take him out" (or like a Schumacher move at Monoco) why would he stop?
I think when guys race at this level trying to achieve these type of results...things happen.