@TM Just like you have your own views and stopped watchin the show because of your own reasons others also have their own reasons for to continue watching the show.
If you like Pratyusha and stopped watching because she is not there there are others who apparently like Toral and are watching the show.
There are other people for who character is important they decide to watch no matter who plays the character.They may have problems accepting the new actor playing the character but still decide to watch and it is their decision.
There are others who have been watching the show for the past 5 years for their own reasons and if they decide to watch the show till it ends it is their own business.
If you do not agree with the view that character is more important than the actor that is your point of view.
I don't think there is any right or wrong here.Different people have a different way of looking at things.