The US military doesn’t want to sacrifice the capacity to go through the Panama Canal without getting a large benefit.
As to cost, in many ways a cruise ship is a better comparison than a cargo ship. The giant crew needed to maintain and operate a large aircraft fleet themselves need support staff, supplies, housing, etc. Carriers are expensive because of the people and systems onboard not the size of the ship.
Even just moving aircraft up and down from the flight deck requires a massive and thus expensive system. Civilian nuclear reactor are hideously expensive to build and operate let alone a system designed to ramp up and down more quickly, operate on a moving ship etc. Close in weapon systems have limited field of fire when you want a clear flight deck etc.
So sure, in theory you could just say we want a larger flight deck and are going to just have a number of empty components to pad out the ship but it’s not so simple.
The US sacrificed that a long time ago, when it first introduced supercarriers in the 50's. Too tall for the bridges, too wide for anything but the Third Locks era, and then only with some minor alterations.
Now that we do have the Third Locks, I think it would be reasonable to replace the bridges and make the alterations, a rounding error in the CVN budget.
Repositioning is far from the only concern but it is something they care about. For example the USS Dwight D. Eisenhower crossed the Suez Canal in 2021.
As to cost, in many ways a cruise ship is a better comparison than a cargo ship. The giant crew needed to maintain and operate a large aircraft fleet themselves need support staff, supplies, housing, etc. Carriers are expensive because of the people and systems onboard not the size of the ship.
Even just moving aircraft up and down from the flight deck requires a massive and thus expensive system. Civilian nuclear reactor are hideously expensive to build and operate let alone a system designed to ramp up and down more quickly, operate on a moving ship etc. Close in weapon systems have limited field of fire when you want a clear flight deck etc.
So sure, in theory you could just say we want a larger flight deck and are going to just have a number of empty components to pad out the ship but it’s not so simple.