The Delving was a cool place in the moors, it broke up the monotony of the regular map, was often an escape from the lag, let you get around the map quicker, also the whole nostalgia factor of needing to get the spirit stones back in the day down there and it being in the game this long. It also had a close quarters dynamic the open map doesn't have. There was basically zero downsides to it it was just a cool little thing to have in the game that had been around for forever until it got taken away out of nowhere with zero rationale or explanation whatsoever from the devs. They basically did the same thing they did with Osgiliath where they said they were taking it down for "maintenance" with no timeframe and its just been down for years now. Also the Osgiliath map was fine, people rank farmed there but they do it in the regular map anyway, should bring that back too