We could put new Central portals at the outer stations that do not currently have a wilds or nether portal. No station would have both a nether/wilds portal and a Central portal other than at Central itself. That would mean a minimal train journey to get between different places on the wilds/nether maps, it would not be just a portal hop.
Having distributing portals to the wilds and nether is very helpful to ensure that resources are not overally depleted in just one location. Wasn't that the reason given for distributing the additional portals at the outer stations?
Doesn't my suggestion sound like a good compromise to make travel around a little easier but not too easy?
And if it is decided to remove the peripheral wilds/nether portals, you might as well save system resources and generate a 50% smaller wilds/nether map. The outer reaches of the current map would be pretty unreachable and seldom if ever visted.