Kesubos 52b - Going against Hashkafas Hatorah

I found the gemara's question of "Since the torah says that a son inherits, not a daughter, how can chazal be mesaken inheritance for the daughter" (since giving a significant share of his nechasim to his daughter as a dowry would reduce the inheritance to his son), to be very insightful. The institution of kesubas b'nin nikvin would not contradict yerusha head on, rather it would circumvent the issue of yerusha, nevertheless chazal feel that it is inappropriate for the Beis Din to set up a system that will legally circumvent the ratzon hatorah. This gemara would seem to be a very strong support of opposing both heter mechirah (even if it is legally binding, which is a major issue in and of itself), and even heter iskah. I am not bothered about mechiras chometz because it is clear that the ratzon hatorah in that case is to have an outcome where a jew does not own chometz (the achronim just discuss maybe there is also a kiyum of burning some chometz), but it is clear that the ratzon hatorah is not to eradicate chometz from the world. Therefore, the only issue by selling chometz is whether it is ha'arama, but it does not circumvent the ratzon hatorah. I am also not bothered by writing a will that accomplishes leaving inheritance to daughter for 2 reasons: 1. it is not a takanas beis din, rather a personal decision. 2. the gemara itself finds a source in divrei kabbala for leaving over something for the girls. But, both heter iskah and heter mechira are systems that are encouraged by the beis din to circumvent the ratzon hatorah which is clearly to lend without ribbis and to not work the land during the shemittah year.

Any thoughts?