The thing to consider however is: how many people have actually A/Bed the Edition 7 and 9 side-by-side? From the few A/B comparisons I've seen, they are actually quite similar. You are correct in that the Edition 9 is the preferable of the two in those cases usually, but my understanding from reading impressions is that the difference between the two isn't very big. Of course, the subjectivity of this hobby makes that difficult to assess just based on reading the thoughts of others, so who knows.
I will add however that the Edition 7 was released at a time when Ultrasone wasn't as well known, and it's price was so outrageously high that people were literally flabbergasted. If you go back and look at the few Edition 7 launch threads on head-fi, you'll see people were already pretty cynical about the Edition 7 before even listening to it. I think that could have a lot to do with the reports of the Edition 7 being so bad: far, far fewer people have listened to the Edition 7, and with it's ridiculous price and expectations surrounding it, I can see a biassed assessment not being out of the realm of reasonable possibilities.
When the Edition 9 was released later on, Ultrasone was going through a period of FOTM on head-fi. It was not only (relatively) less expensive, but many, many more people got to listen to it, and by that point the perception of Ultrasone had changed somewhat. I say somewhat, because the Edition 9 is still controversial. If you look at impressions, you'll see some people felt / feel it's a "sibilant little monster" too. There's usually more variation within groups than between groups, so to speak.
I think attitudes toward the Edition 10 lends a certain credence to the idea of history repeating itself. Like the Edition 7, Ultrasone released a ridiculously expensive headphone that underperformed for people's expectations. Perhaps they thought they could "get away with it" now that they've earned success with the Edition 9 and then Edition 8.
