haleivi: i’m not sure i follow you. rishonim have often dismissed explanations brought down in the gemarah or mishna as non-pshat. the only rishon i can think of who tries to force pshat into every opinion of the tanayim and amorayim is rashi. so they dont necessarily take on chazal they simply relegate divrei chazal as non-pshat.
as a total aside, there is a very good reason to attempt a rational explanation when possible and its right here in this week’s parsheh:
? ?????????????, ???????????–???? ???? ??????????? ????????????, ???????? ?????????: ?????? ???????????, ??? ????-????????? ????????, ????????? ??? ???-????? ????????, ??????? ????????? ??????
the rambam looks to these words as a driving force to not give explanations that rational people will look at and say “what a small and ignorant people these people are.”