IMHO, if we were living in a ideal world where RN has enough money for all it's basic needs ( including manning ), then I would say that having one or even two dedicated hospital ships wouldn't be a bad thing at all.
But, considering that funding ( and manning ) is so scarce that the RN is forced to do constand juggling with money and personell to cover even the most basic tasks ( carriers, escorts, amphibious ships etc. ), to spend these scarce resources on dedicated hospital ship is nonsense. The only way I could support it if these ships would be: a) multifunctional ( like say RFA Argus, for training of helicopter crews ) and b) at least 50% funded ( in buying and operational costs ) by other departments ( like Department for International Aid and Development ).
So, IMHO way better option would be the spread of medical facilities over various RN/RFA ships ( like carriers, LPHs, LPDs, LSDd, fleet tankers, FSSS ships etc. ).
Fortune favors brave sir, said Carrot cheerfully.
What's her position about heavily armed, well prepared and overmanned armies?
Oh, noone's ever heard of Fortune favoring them, sir.
According to General Tacticus, it's because they favor themselves…