Milo
They are certainly a way of deploying all manner of assets including aircraft both rotary and fixed wing (albeit now STOVL) to anywhere needed to serve UK interests. However HMG has called for a re-establishment of our Carrier Strike capability and the events of this week confirmed that 2020 was the absolute deadline for this.
The carrier(s) are not "primarily" for Anti Submarine Warfare or another layer of Fleet Air Defence as was the case with the Invincible Class until the Sea Harrier was binned. Clearly, they can contribute to both but these are secondary roles. They will therefore train for and expect to go in harms way when required to do so by HMG and will take what they need with them as well as being re-supplied at sea.
What the USMC wants to do with their F-35B's is another issue and something many remain to be convinced about. When not operating from a carrier, how do you forward deploy a fifth generation aircraft with a stealth coating?
Anyway for the UK as well as the USMC, the F35B seems to have become the only choice for varied reasons!