Did the DVDs not sell well?
The first season was released by AnimeWorks. However, they let go of the title after that and ADVision picked it up and released the second season, FLIGHTS OF FANCY. However, the second season of AH! MY GODDESS! became one of many shows of which ADV sold the rights to Funimation. (This was sometime before ADV went completely bankrupt.)
Did this show not gain enough popularity here in the US? It's an anime of one of the better known and loved manga series, it's got beautiful artwork, the story is solid and the characters are enduring and well fleshed-out. The dub is wonderful, the actors all fit the characters really well. ADV, thankfully, was able to get the same cast of American voice actors to return to their roles for the second season, and the FLIGHTS OF FANCY disks came with voice actor commentaries.
Also, I understand these first two seasons are all that have been made so far of the TV series. So, did the show not do well in Japan, either? I mean, there's so much more manga to cover!