These massive, monolithic 400+ episode runs are not doing this show any good. I wouldn't be surprised if actors are feeling fatigued and suffocated, so they move on elsewhere. Of course, these shows run five days a week, but they run throughout the year, which may strain the actors a lot. Not surprisingly, those in search of other or more work have left- first Shakti, then Sneha, and now Vrinda- and they couldn't get much out of the guest stars.
So if this show was running at 22 episodes a season, or maybe 60 (for five-day weeks) episodes, and then take a break, and then come back, would the show be better? Not only would the actors and writers get to pursue other interests and projects, they would also come back refreshed. It would also help the story stay consistent, and also the acting.