Considering how little kids read at all, expecting them to read classics is like expecting them to walk on water or turn water into wine. For most of them, just reading the Harry Potter series should be cause for celebration by their parents and teachers, because even in that bit of light reading they will come across words and ideas they otherwise wouldn't. Most works in the Fantasy genre aren't classics and won't become them, but that doesn't mean they have nothing to teach children. From vocabulary, to grammar, to reading comprehension, all of these things can be improved by reading any sort of book, and the point of genre fiction is to make reading books as easy and enjoyable as possible. It's a way to start reading, to gain a taste for it, and then to move on to other works and genres. Your condescension is the reason why kids beyond elementary school age aren't encouraged to read such books, and it does a lot more harm than good.

As for Xbox, you're right, it certainly doesn't help anyone mature. But there have been numerous times when names and ideas used in video games prompted me to research them online, and find things ranging from mythology, to psychology, to physics. Perhaps these are things I would have discovered anyway at some point in life, or perhaps not. All I know is that video games are responsible for some of the knowledge I possess, and that means they have some value beyond "mere" entertainment.