OK,so I totally got that, but who cares?
Who cares about the themes of the movie? Mike Leigh, probably.
I do too actually. 'Who care?' What's that supposed to mean?
I actually wish the value of theme would be challenged a little more, in a way. I sometimes feel like ninth grade literature teachers everywhere have brainwashed people with the belief that thematic elements have some sort of a priori worth — as though a movie or book with a subtextual leitmotif connecting women with water is automatically improved by such. Critics fall into this trap quite often, I think, where the recognition of any sort of underlying thematics inflates the critics' self-worth ("look what i noticed! see how clever i am!") and in turn leads to them inflating the film's worth. Or something like that.
It's not that the spotting of a theme automatically makes a film better, it's just part of the reception/interpretation of a movie. Art is supposed to have themes (and everything does, good or bad), and interpreting them is part of the process.
Either way, in the case of "Naked" the subplot he was questioning wasn't subtext (Like "Women and water"), it's text. There's a reason for it to be there, and it's part of what the movie's about. This isn't trivial, or a non-sequitur, or there for the critic to blow smoke up his own ass. It's essential to the movie.