I think the makers of NP gave us the best suitable end to the show. I know it was sad but it was realistic. Iqbal would not have been able to enjoy a normal life with Meher, no matter how much he wanted to. Yes he loved her and we the audience know it. Even Meher was aware of this but circumstances and destiny were not in favour of the tragic lovers.
Meher surviving after Iqbal's death would have meant that she would live as Sameer's wife. And that would have been wrong. As they say, pyaar mein zabardasti nahin ki jaati hai. Had Bebe forced Meher to become Sameer's wife, it would have been unfair, not to mention distasteful.
It was a heart warming end to see Sameer with Iqbal and Meher's nishaani. Sameer was indeed a nadaan parinda and the same can be said of Meher and Iqbal's child. I am sure he will teach the little parinda to fly and touch new heights :)
The heavens must have opened up for Meher and Iqbal to meet. Log guzar jaate hain lekin pyaar zinda rehta hai.
:)