Personally, I like the idea of diversifying the fan bases, rather than just sticking with one thing; make it more likely to have people relate to the contents. That's actually the main reason that I didn't care so much for the Anime Hunters' videos; they were heavily Final Fantasy based, and I've never played the games. Except in cases that were overall funny, most of their jokes made no sense to me. They countered that with having the occasional non-FF cosplayer, which was nice. Hetalia would run the risk of similar problems, possibly even worse, since less people are familiar with the series.