I may be missing something here, and I am far from being an apologist for Hilton, but I can fully understand their stance on no longer allowing same-day cancellations if the practice of booking a room just in case there are flight or other travel problems is as widespread as it seems from the above comments. While they can overbook, just like airlines, if there is inclement weather they would end up not only having to accommodate more bookings than there are rooms, but they also have no rooms for all the other travellers affected by the weather.
On the other hand, this practice, for al I know, may only affect airport properties, so perhaps there is room for Hilton to finesse the requirement by limiting it to certain hotels only.