I know, I went back and forth on that one. The deciding factor was the popularity of betta. I figured since they are so popular it made sense to have them toward the top since more people would be looking for them then anabantids. Same with livebearers, they are so popular.
Maybe it's just that I got used to it, lol. Anyway, it works by popularity also. Alphabetical is fine too. Putting them both under "Anabantoids" would scare away the newbies since they probably don't necessarily know Bettas & Gouramis are both from the same family.
All in all the changes are great.