I agree with you about Saint Seiya becoming commercial, but it's was forced when a shonen manga became a success. Look at Naruto/One Piece/Bleach/Dragon Ball ^^.
And OK Asgard was a filler commercial arc but it was one of best arc of Saint Seiya in my opinion. Commercial doesn't mean it will be bad (ok, a lot of commercial things are bad).
There are some people who say that Asgard Arc is the best arc of Saint Seiya!
I think this arc is not over rated, it had some beautiful and interesting character. They have a very good background (compare to Gold saints or others...). Now we have ennemies who have their story (Mime is an unforgeattable character). It's not a manichean fight, there are not really good and bad.
http://www.youtube.com/watch?v=qeedFRI4Fxg Mime Benetnasch
http://www.youtube.com/watch?v=TFtZPZpNIQs Siegfried Dubhe
About Poseidon arc, I don't know if it is over rated because a lot of people say that it's a shi!?! And i'm in!
Toei Unanimation does Inferno and Elysion, I don't want this compagny touch again Saint Seiya >_<. Disney and Dreamworks, i think it's a dream
. But Madhouse, IG Production, why not? Well we have TMS with Lost Canvas, and their work isn't bad.
I hope OAV of Lost Canvas will have some success so we can have a sequel of these 13 OAV . But Manga of Lost Canvas uses a lot of commercial things like fan service which is a little irratating when there is too much of this shi!?! And Shiori seems to extend the story...
I hope Lost Canvas will end gracefully too.
You're right about success is not alway "good" for a manga. But when you want to have success, you need to attrack more reader... And fan service attracts mens
. It's not good too >_<.