It was split because the 1.0 city zones were... frankly... utter torture to navigate (Gridania being the worst of the three, having to tromp down long corridors or tunnels just to get anywhere.... urrghhh.. 'Emerald Labyrinth?' More like emerald nightmare!), and it was due to the city zones actually not really being one large zone, but really several combined together and their zonelines concealed by said corridors (you could actually tell in 1.0 when the zone line changed due to the client momentarily pausing for a split second and the map then updating), and was a major complaint of 1.0 players. So no wonder Yoshi changed this.

The current zones are fundamentally the same size as they were in 1.0 more or less, all SE did was take the blinders off by abolishing those long empty corridors and gave a proper zone change and split the map up into what they really were. So going back to those old days would not solve anything.