If one tries to be totally objective there is much logic in the provision of all air power from an independent air force. The Army and the Navy are utterly professional in their own roles and, similiarly, so is the Air Force in theirs. To assume that within any one of the three services one could muster and maintain the level of expertise and experience to perform satisfactorily the role of any of the other two services diminishes the credibility of separate armed services.
The RAF is not clamouring for tanks or ships so why do the other two services want their own air power. They should accept that if they want air support and don't get it there is a very good reason - someone else needs it more. In these austere times it is vital to apportion one's resources so that they can be shared according to the priorities of the moment - not held in reserve by a force that does not need it at the time or equipped solely for naval or land force support.
The only sensible alternative is a combined force structure. I spent some 36 years learning to do my single service job and was still learning when I left. OK, some are slower than others to grasp the knowledge and to cope with rapidly changing technology, but I could not envisage a combined service doing any one of the single service roles in the same professional way.