This is a key aspect. There is a pressure (both institutional and self-imposed) to produce something original and unique, so trying to reproduce other people results is seen as a lost of time.

Either you confirm previous results, which is nice but not something you can publish or write a thesis about; or you find they are wrong and then you have to tell the authors, which is something they may appreciate or not, and be exhaustive to prove it, which is something in which you may be interested or not.

What I would like to see is that PhD students were required to reproduce some previous results as part of their thesis. This would increase the quality of scientific results and would prepare the candidates to do their own research (at difference of now, that they are put on front of a laboratory to get "interesting results" and they don't know what to do with it).