I think its location is a big concern, as its on the diverting line (connecting too can be termed) from Udaipur-JP & ADI-JP!!
Nathdwara falls like Bulandshahar/Azamgarh are placed just away from the main connecting tracks!! To connect UDZ-JP/ADI-JP Track, only Passenger Service may run, as train if diverted, will not be of any significance for travelers & no big place comes in between. Even UDZ-ADI do have just two trains!!