I love Balto, and personally I think it's quite underrated. It's based on a true story, it's got good animation and is overall quite beautiful. Personally, I like watching it in the holiday season because of the snow.

I don't know exactly why it is so underrated, but I'm guessing part of it is because it's not a Disney movie. Many movies get overlooked simply because they are not Disney/Pixar, which is a shame because there are some beautiful non-Disney animated movies out there. Balto, The Land Before Time, and Spirit: Stallion of the Cimarron being some of them.
I also don't think enough people have been exposed to the movie. Once again, Disney is the most popular choice for parents when they want to get their child a movie, so Balto is often overlooked. Also, I am not entirely sure if Balto is still in stores, I haven't seen it for a long time, that's for sure.
So between not being Disney, and it being an older movie, it simply doesn't get much publicity.
As for the message boards, I think most of the boards die because most of Balto can be discussed at Animation Source. And I think the Balto forum there died because there's nothing left to discuss after however many years that site has been up.
... I think I just rambled a bit.
And Juhouh, it's a movie worth seeing.
