I really don't see any reason behind this when there are no posts under hakke.
Posted under General
Alright, but then why wouldn't we alias both to eight trigrams? That would be the most useful to the site's userbase, which is primarily English-speaking.
Problem is it's not a Western concept, and no one has had a widespread problem with ba_gua, otherwise we would've noticed it with hakke and eight_trigrams, which are empty.
Just alias hakke and eight_trigrams to ba_gua; even Wikipedia redirects eight_trigrams to it.