As an OT fan that does like the prequels also, for the most part, I think the kid has a point about the characters. You may say Anakin is whiny sure but there is at least abit of depth to him as compared to say Han Solo. Its interesting that Han was my favorite character as a kid and now I can see what Harrison Ford was talking about in that he had no history or real point to the story past ESB. All we know about him is that he rescued Chewy from slavery and that's in the backstory novels that you had to read besides seeing the movies if thats even Canon.

The Prequels also have a large scale epic quality to them in terms of scope (large armies assembled etc) that makes the OT seem abit smaller in scale. I think to a kid growing up now who is used to CG movies, the OT's smaller scale will definitely make an impact on what they prefer. And to be honest those large assembled armies were in Lucas' original draft (which is why I like that epic scope the prequels do bring).

Now that Disney is basically retconning out the prequels (its shocking they are letting the remaining Clone Wars episodes out there) we're going to see more of these types of fans come out and get vocal about the prequels and what they find good about them.