"Why do you think NATO considers the carrier to be of extreme importance and aside from Britain, France, Italy, and Spain all have a carrier capability?"
Possibly because the Americans provide all of it for free? The UK has 2 small unreliable carriers that have a handful of jets (and a promise of two squadrons in 18-24 months - wow!), The French have single carrier, The Italians and the Spanish have a glorified, aging helicopter carrier each - the Spanish vessel is no longer listed as an Aircraft Carrier but as an assault ship. The rest of NATO doesn't bother
All together they have less , a lot less, capability of a single US carrier