A Virginia can carry the same amount of CPS far cheaper, and building a 17 billion dollar ship to throw shells 90 miles is stupid.
As an avid submarine supremacist that's true, but a Virginia is limited in what it can do, being offensive actions against surface ships, submarine warfare, general area denial and collecting intelligence passively.
But something like BBG(X)/BBGN(X) can fulfill various missions, some of which not doable for a submarine. That includes anti-air warfare, ballistic missile defence, land attack (which can be done via sub too, to be fair here), ASW (also doable with a sub), serving as either an escort, independent asset or a capital ship for it's own battlegroup. Ideally it can serve as a command and control asset for either surface strike groups or air warfare groups. It's worth keeping in mind that the missile cruisers with large VLS count and dedicated flag facilities are going extinct and the AB Flight III is not a one-to-one replacement for the Ticonderoga. Furthermore the Blue-Ridge Class ships are bordering on ancient, albeit equipped with less dated subsystems, but for those there isn't a replacement in sight either. So you'd like to get a ship that can take up the legacy of the Ticonderoga-Class, take up some of the burden of perhaps even the Blue-Ridge Class and provide the firepower the ill fated Zumwalt-Class could never deliver (not even after the late and costly CPS refit).
There is plenty of merit to the general concept of what's proposed, but information of the actual proposal itself isn't concrete yet or even at that stage at all. But generally speaking one cannot go wrong with a capable surface combatant that offers plenty of growth potential for the future, defensive and offensive capabilities exceeding those of current USN ships and the autonomy to operate globally even on it's own or as a centerpiece of a small action group.
If these advantages are worth trading in yard space that could be taken up by a CVN otherwise, that's for others to decide. Probably depends on how much emphasis one puts on the SCS scenario where a CVN is essentially dead once in range of one of the various missiles posessed by a certain East Asian superpower.
