Where is there a khuta tanne here? It is all a debate for and against dual citizen. Even if they get dual citizen, I doubt how many will come forward to take ? How many of NRN have that NRN card first before advocating for dual citizen?

American citizen need visa to go to other countries too. Check the net.
NRN card allows 10 years visa so where is the hassle for 10 years? For all other countries with your US citizen, you won't have travel problem. 

FYI Nepal give Bridha Vatta once you reach 65 or 75. Rs 800 a month. You NRN want that? :)