
1. I think people are essentially correct to worry that a hypothetical YA Hugo Award would get voted on by people who read only a little YA, not a lot, and so the award would kind of default to "that guy I've heard of who wrote a YA book this year."
2. But honestly, you could say that about lots of the awards. Dramatic Presentation, Short Form tends to be the "What was the best episode of Doctor Who this year?" award, and I don't think most of the recent Best Novel winners were actually the best SF novels of that year.
3. Nor do I think that a YA Hugo would help to convince young people to attend WorldCon. If you are young, WorldCon feels like a convention where you don't quite belong. The reasons behind this are many and complicated, and other people have gone into that better than I could, but nobody's going to think, "Well, this convention sounded kind of boring, and I would have to fly there and get a hotel room and it would be expensive, but I would get to vote on the YA Hugo!"
4. There are two main reasons it's nice to give out an award. The first is to bring more attention to really good work that otherwise would fly under the radar. Except in the fan categories and the short fiction categories, the Hugo doesn't really do that. The Avengers? John Scalzi? Doctor Who? WHY THANK YOU I WOULD NEVER HAVE HEARD OF THESE THINGS WITHOUT YOUR HELP. Which is not to say that the wrong thing got the award -- I personally would've gone for Cabin in the Woods over Avengers, but it's a legit choice, and very often the best episode of Doctor Who IS the best SF on TV in any given year. It's just a marked contrast with an award like the Printz, where a small committee reads a megaton of stuff and often chooses things that are quite obscure and deserve more recognition.
The second reason for an award is to build up a canon for people just starting to become familiar with the genre -- I've relied on the Hugo and Nebula and Tiptree awards in this way, myself, as well as the Printz and Newbery.
I feel like the Printz award has not really been successful in building up that kind of canon. (Out of 14 years and 60-ish winners/honor books, I can think of 7 books that would make me think, "Yeah, you definitely ought to read that if you're professionally involved in YA." -- not just that it's a good book, but that it's still being read, that it's become part of the canon. I acknowledge that 'canon' is a problematic concept to begin with.) Is it because YA is too ephemeral and fast-moving a genre? Is it because the obscure, quiet, offbeat books favored by the Printz just don't have enough teen appeal to gain traction? This isn't a problem; it's not the point of the award to predict what people are going to be reading in 10 years. But I feel like, if somebody wants to read the essential important SF of the 60s or 70s, the Hugo is going to give them a pretty good list to choose from, and I would be very much in favor of a YA Hugo award if I thought it could play the same role. I'm still undecided on that point.
5. Regardless of whether a YA Hugo is a good idea or not, it's understandable that the "objection to consideration" FEELS like "Go away, we don't care about you." I felt that way myself when I heard the news. And I have no doubt that there are a bunch of people on the committee who think that there isn't work coming out of YA fiction that has true literary merit that deserves to be recognized, or who don't want Those Young People changing the atmosphere of their convention.
6. I think that out-and-out fantasy and science fiction (as opposed to magic realism, ambiguous-reality kind of books, etc.) are a bit underrepresented in Printz awards; there's often just about one honored per year, sometimes fewer, rarely more. (Typically they have one winner and four-ish honor books.) Additional award recognition for great YA science fiction and fantasy would be nice. It's good that we have the Andre Norton award, but -- more would be nice.
So. It's hard to convince me fully to be either in favor of a YA Hugo or against it. I lean to the side of "I would be really interested in how it would work out, if they tried it out" -- and if nothing else it seems a bit more relevant to the larger world outside WorldCon fandom than "best fancast."