Honest curiousity: Why do some people reject Hadith?

as there are lot of contradictions ...in the hadits ....then actions /wars /slaughtering ....which indicates that peoples forget to behave like humans .....but groups supporting these .....needs new generation for rational ysis ...of all the compilations...impartially ......on the basis of humanism ...and hadits has to be in line with holy quran ..... thanks salaam