Most of those rumors about where DBZ was originally meant to end are false, though. Dragon Ball was originally meant to end after Goku first collected all of the Dragon Balls. However, fans wanted more, so he continued. From that point on, there wasn't a single point in the story where Toriyama thought "Okay, I'm done", except of course for the end of the Buu saga.
He never said that he wanted to end DBZ at the Frieza or Cell sagas. The whole point of DBZ at first was to slowly transfer the role of the hero of Earth to Gohan, and continue the story from there. He changed his mind in the Buu saga, though, because he felt that Gohan wasn't suited to be the hero.
As for the whole Super Saiyan thing, I didn't mind it in the Cell saga when other people achieved it, because they still either had to work for it or experience some extreme emotional anger or sadness to achieve it. It got slightly out of hand in the Buu saga when Goten and Trunks achieved it so easily, but a popular theory is that they got it quickly because they inherited the Super Saiyan gene, since their fathers could achieve it by the time they had........impregnated their wives.