If the "how to get into voice acting" panel is done again, it'd be something for them specifically to look into. Printing the papers, ink, and organizing everything takes time, coordination, organization, and money. Which while some people have the time and energy to devote to this, some may not.
If you're concerned about it, why not make the little fliers yourself? Include some information on how to get into it, perhaps with some names and locations of local theater groups, or websites to information that explain further then a sheet of paper could. Then you yourself should find out and get in contact with those who run that panel, and perhaps see if there's a way the Panel staff can help integrate these fliers to be available at all of the voice actor's panels. So if the question is asked, they can just say "I have a flier here that you should come up and grab when the panel's over." Or have at the start of the panel a clear statement that the fliers are available for anyone who wants to come and grab one. I dunno, maybe have some stashed at the Info Booth as well- if they have room of course. It'd take a lot of coordination and asking the staff, but it could be possible surely.
Specifically for Hetalia and Homestuck panels, I'm back and forth on whether I like there being 'so many' panels or not. But I could just as easily pin it on some other large fandom that I dislike and say they have 'too many' panels.
The question for these coordinators is how much is 'too much'? Did they really get a good turn out? And who are the ones complaining about them being too many- are these fellow panelists whose idea was shot down, or just attendees? Are these panels being run by different people, or will they be run differently then before to keep a diverseness within the panel itself? It'd be honestly no fair for the coordinators to go to ALL of the large fandom panels and request extended information for what their panel will include without them having to ask all the panelists to do this.
Panels are also a hit or miss. My Shakespeare panel, for example, has had a huge turnout at Sakura Con both years I've had it, but last year at Kumori the group was hardly 20 people. Both groups, regardless of amount of people, were sincerely interested and enjoyed the panels and interactions provided.
Sure, I want more variety of panels being submitted, but it also depends on the panelists. Will the attendees become a panelist and take on that dedication to plan, coordinate and perform the panel? And will past panelists decide to not have X-Panel anymore?
Let's say someone went to a Hetalia panel at Kumori in 2011, thought it looked fun, and put on their own Hetalia panel at 2012 and are planning another for 2013. Would you want to tell them not to host a panel for a fandom they enjoy simply because of a percentage of attendees think there's 'too many' of that fandom's panels at the previous year?
That said, I really applaud all the panelists each year for the variety that they do present us with. Even if I can't attend every panel I want to, there are a lot that looked like they might've been pretty interesting to sit in on from years past. And really, if the Panel Coordinators can organize all of our crazy panels, that's a pretty impressive thing- to think of the rooms, the times, the Guest's, opening and closing, requested times. To ask them to inspect to make sure there aren't 'too many' of a single fandom's panels going on seems kind of much. They already are probably doing that, like I said before.
If anything for critique to fellow panelists, panels longer then 2 hours... Oh my god. I don't want to sit there that long. I'd feel bad coming in late, or leaving early. But really, if they're going to have a panel that long, can't they just break it up and request for 2 panels and have a very specific dedication for each panel? Yes, some panels have to be an hour long. Thirty minutes goes by fast, and a full hour is great. But I don't think I've ever needed over a full two hours, even when I've requested it.