for once in a while tourists like us, yes. But for people who stay there and have to use these lines the small size of MG/NG trains reduces number of passengers it can carry and also devoid them of direct connectivity as they have to change trains to get to main network. Not to mention its rolling and traction stock is grossly under-powered.
barring some heritage networks, like those on hill station where most people using them are indeed tourists the gauge conversion projects is actually one of the better things about IR.