I don't mind that the other Bronze Saints don't show up. I think its more interesting to focus the story on other characters and especially on the Gold Saints.
Afterall, maybe Seiya is the reincarntion of Tenma but that doesn't mean that the previous life of the other saints must also be the same saint or be be any Saint. (eg. I don't think that Deathmask and Manigold are the same person)