It is true that the nukes power is mostly in forcing anti's, and thus this power scales if there is more territory to be covered. I haven't seen these new big maps played with nukes but I can imagine a map large enough that building nukes is a no-brainer.
Dust bowl is big (24x16), but there are maps of comparable size: Tempest (20x20), Tropical (18x20), RiverMouth(20x20), MoonQaurtet (20x20), Rage (20x20).
Reducing the range would also effect the balance on FFA maps, which are routinely much larger (24x24 such as Mosh Pit, Throne). I feel nukes are balanced on FFA maps.
If this is indeed a problem, I think it is a problem created by the inability to cloak anti-nukes. This is a GOOD change, but it is a buff to nukes: If you have a complete scout of an area, you know for sure whether you are firing into an anti or not. Previously, a lot of nukes would whiff on Anti's. They're also easier to snipe.
So, IF this is genuinely a problem, I'd suggest brining the cost of antis down a bit to compensate for their inability to cloak.