Esha a very good post.
Won't say about Dadisa because much is said about her and we have seen her evolve over time.
DB - First of all I don't think she was regressive and a is tradionalist with a conservative mindset.Had she been that way from the beginning she would not have married against her family's wishes or run away from home.
But later on the circumstances which in her life made her turn regressive and rigid probably to escape the miseries of her life she turned tradional and developed ths regressive mindset aout everying old is gold and to add to that she is selfish spoilt and like Sanchi.
Where bitter experiences made Dadisa a better person they brought out the worst in Dadibua.
As for Bhairon Singh not leaving DS or unable to change her it's more to do with his love for his mother and willingness to put up with her ways.But Dadisa changed after Jagya left her.She changed her views after her most loved one left her and the loss made her realise what is more important in life.
Here why DB's husband and son left her is not very clear.It may have been their nature and combined with her own nature of selfishness and wanting to be centre of attention and wanting to have her own way.
DS's views have come from the way she was brought up and DB acquired them along the way probably as some sort of a shield.