There are many who insist that there is a higher, more complex form of Greek cookery to which we mere tourists are not exposed. I'm sure there is. (The mischievous part of me is tempted to say: yes, it's called Turkish, which has a truly fabulous tradition. But that would merely be courting controversy, and you won't find me doing such a thing.) I do know that Greek wines go far beyond Retsina, that there are some intriguing reds to be had if you know where to look.
What we probably have here is yet another superficial, stiff Oxbridge twit (he actually went to Leeds, but I'm on a rant here) who believes that he is an authority on world foods. The challenge with Greek gastronomy rests on those who have inherited the tradition. It is they who must convey and market the true essence and diversity of Greece's foods. It's a tradition that is more than just feta cheese dumped on top of something cooked in olive oil, Mr. Rayner.