Why supercarriers mattered to nuclear strike planning

Were CV-58 and the Forrestal class intended partly as platforms for nuclear-bomb aircraft?

Yes, but they also existed to generate the scale of carrier strike force the US Navy believed it needed against modern air defenses.

Cold War carrier planning treated force generation as a calculation of how many aircraft were needed to penetrate a specified air-defense problem. Nuclear delivery mattered within a wider naval requirement for sustained deployable striking power. CV-58 and the Forrestal class needed the deck and hangar capacity to operate heavy nuclear-capable aircraft such as the A3D. Their size also supported a larger conventional air group, so the same hull investment remained useful even when the target set or weapon changed.