People do take suvidha when they can't find tickets in other train. That is y, KCVl-BNC Suvidha was announced in budget, with only limited run. But, yes all are not rich to afford it. And Karnataka is not just SBC.
But special train request has to come from SWR, just like SCR came with special. SWR is not much bothered about specials. SR will never think of special from Rest of SR to Karnataka. SR special is always train from MAS/MS or via MAS/MS