That's true.
However (to elaborate my original point, rather than disagree with yours), we may with confidence recognize that a person is in heaven, and that he lived an exemplary life, without reaching a conclusion regarding the prudence of his every act or every impact of his life.
These are the kinds of questions always open to re-examination. Policies of President George Washington are still debated, for example, and there's no reason they shouldn't be.
I agree with your point that canonization does not in fact endorse all aspects of the policies, but rapid papal canonization tends in that direction. No popes have been elevated this rapidly in at least the past 1400 years, and it seems to me the rush is more a self-administered pat on the back to assure ourselves that things are ok rather than because the ones being canonized stand head and shoulders above all their predecessors—and pseudo-equivalent canonization in the case of John XXIII (waiving the requirement of a miracle after beatification), makes this seem even more the case.
The rush to canonize made feasible through the easing of the traditional standards makes it so that the quite good and truly outstanding get lumped together and makes it more likely that the person will not be seen in historical perspective. Four miracles, or three miracles and martyrdom, was a much taller standard.
http://chiesa.espresso.repubblica.it/articolo/1350746?eng=y