These rule (white dress on husband's death) and many other are set by humans (males) not by God! Males always prefers himself superior than females and with this arrogance of themselves they put lots of restriction on women in earlier time like...
- They have to burn herself with husband's body.
- Later they change a little and impose new rule on women that they have to wear white sari after husband's death.
These rules are imposed on women in name of Parmpara or dharma But actually these rules has nothing to do with dharma. How in the world a dress code can decide whether you are a Dharmatma or not lol.
Let me give you an example through which you will come to know that these rules (parampara) doesn't make a woman Dharmatma or anything like great.
Once Shree Ram said to Lakshman that Man can't be a saint or branhman by his birth but instead he can be by his karma (Deeds that man does). Even if you are son of a Maharish that doesn't make you also a Rishi but your karma will decide what you actually are... This is the reason, Maharishi Vishwamitra is know as the great Brahma Rishi instead of a great king (Vishwamitra is a son of a king) And Bhagwan Parshuram knows as Kshatriya more than Brahman (His father Maharishi Jamdagney was a Great Maharishi). Both of their karma was apposite of their father's that's why they are not famous for the same thing, for which their father was.
Hence your karma will decide what actually you are, not your birth or your father's karma. And to be more clear, Dress code (whether white sari or saint cloth) has nothing to do with karma or dharma.