More than the cast, it is the writers and directors fault.
About old cast. Except for four or five who gave flawless performances, others had flaws and were not consistent enough. But what made them admirable was the zest they showed and they were lucky enough to get the best scenes. And they had the advantage of working in a brand new show unlike the present ones working in a show that is not new but went on and on.
So I will give some benefit of doubt to the new ones.
Mahi is connected to anandi becausing she is portraying her daughter and we all know how the daughter was. A spunky girl taking impulsive decisions and fun loving. Never looked bechari even when she was beaten almost to death. So no excuses here.
But Avinash(Dr.Amit) is not connected to Jagya in any way just because he is also a doctor. Amit's way of handling cases and acting will be different and it should be different.
As for Ruslaan, his is also not a new character. A carefree NRI Just like Gulli's husband but he is portraying it in his own manner and its not bad.
So I will give some benefit of doubt to these two.
But I will not forgive the new writers and new directors who have exhibited little or no vision so far.