I would argue both lauding and condemning are problematic practices in most cases.

My history professor in college used to cite the old adage that 'the past is a different country', meaning that one shouldn't pass judgment on the practices of the past just as one wouldn't pass judgment on foreign customs. From a practical standpoint, withholding value judgment is part of intellectual diligence - it allows us to draw interpretations of history and people that don't play on our inner biases. That attitude has tangible benefits for ordinary people in a pluralistic democracy as much as it has for academics - it forces us to dissect the sources of opinions we don't necessarily respect as well as the ones we cherish most, and that dissection is key to understanding (and hopefully solving) the root causes of social problems. Having no one above reproach or below respect - or more simply, having no heroes and no villains - makes us a more mature society.

From a more theoretical standpoint, Edward Carr wrote a famous essay in 1961 (http://abuss.narod.ru/Biblio/eng/carr.pdf) that demonstrates that the most significant work of historians is, like modern scientists, model-building: historians generate narratives about the past, linking this causative factor to this specific result, just as modern scientists construct hypotheses by turning correlated phenomena and causative mechanism. Unlike the physical sciences, however, history, does not have the benefit of falsificiationism or Bayesian confidence - because you can't repeat or vary the same historical incident in controlled conditions, you can never "prove" a narrative incorrect or increase your trust in a historical narrative's prediction the more times it agrees with the facts. Consequently, any historical conclusion we make is always an interpretation of, and not a reliable insight into, how humans and societies behave.

The somewhat upsetting conclusion from this walk down the foundations of historiography is that you can never have historically-vindicated criteria for acceptable or unacceptable behaviour - any criteria we adopt now can't point to a historical narrative for validity, and must seek more robust epistemological foundations (controlled experiments, metastudies, etc.). Until you have such criteria, both lauding and criticizing would, at least to me, rest on unjustifiable beliefs.

(Examples of behaviour criteria that relies on historical narrative for validity and thus shouldn't be applied as value judgments per the chain above: "Treat group X as evil, because group X did so-and-so in the past and we're better than that." or, equivalently, "Advocating for democracy is good behaviour because it directly led to improvements in quality of living in all the Western countries that had it.". These are not my beliefs, mind - just examples of beliefs that rest on historical foundations.)

tl;dr value judgments can't use history as a valid justification because of how history is actually practiced, so applying judgments that do use such justification is iffy. Also, trying to avoid value judgments makes us better at understanding how systems interact, which (hopefully) makes us better at solving social problems.