I also had similar thoughts. Especially, Kathmandu had been an independent country for the most of the history before the unification movement by Prithivi Narayan Shah. And, Kathmandu was a single ethnic state for the most of the history. After unification, Kathmandu is the capital and the cultural city of Nepal. The rest of Nepal was rural. However, that didn't mean Nepal is only Kathmandu. And, no other than the unifier Prithivi Narayan Shah saw this before anyone and said right after the unification - "यो मेरो दुखले आर्ज्य मुलुक होइन | यो चार जात छतिस वर्णको साझा फुलबारी हो ' | Prithivi Narayan Shah said that 250 years ago.

Therefore, I also agree with you Surendra ji that bringing those people together will make the Nepali state strong. Best wishes for your efforts.