I hate when people say stuff like this:
Im not gonna bother giving long explanations since everytime I do I somehow end up banned. So, im just going to say. No, the plot in DB/DBZ is not simple. Its got a lot into it and its actually good. You could make an epic franchise with Dragonball (like Harry Potter or LOTR) if they were done the right way. Theres a lot of good material, story, character development in DB/DBZ to make like 5 or so great movies.
I'm talking about the plot, not character development. There were a lot of strong moments in DB (Goku finding out that he was the one who killed his grandfather, the deaths of Roshi and Krillin, Goku reuniting with his grandfather for a day, etc)
A sequel to this mess? no thanks. Hell, after this bad experience I dont even want a reboot. Just let this great series die in peace. DB and DBZ were the best. (GT sucked), so let it die in piece now.
It can be fixed you know? I wrote a very simplified outline on how they could fix this. Take a look and tell me what you think
http://forums.superherohype.com/showthread.php?t=321041
EDIT: ok im gonna add just a little. If you are talking about DB, not all sagas were the same. For example the Tenshinhan saga was not like you described there, they didnt search for the Dragon Balls in his saga for example and there was no "bad guy to defeat" either, it was only Tenshinhan that was the rival, but he wasnt a "bad guy" of the caliber of Piccolo, Vegeta, Frieza, Cell, Buu, etc. In DBZ there was training (but not tournaments, only in the Buu saga that you had 2 tournaments) all the time, but the plot and story differ depending on what happens on each saga. So, no, the plot isnt simple and theres actually good story in both DB and DBZ. Another example, the first enemy of Goku (Pilaf doesnt count as a real enemy, he was a joke) wasnt a "bad guy" it was actually a terrorist army that was wreaking havoc and chaos in the world, destroying villages and such. You could start a Dragonball franchise using that and combining it with the Piccolo saga, throwing in Tenshinhan too (Tien). Like I said, this franchise had potential. Its all gone and over now.
Again, I'm talking DB, not DBZ. It depends how you see it, for me there are 3 sagas in total.
Pilaf Saga
Red Ribbon Saga
Piccolo Saga
If you see it like this, the thing I've said makes sense.
Search for Dragon Balls
Defeat the bad guy (Pilaf -like it or not, it was the first real enemy, or at least a threat- Red Ribbon, Piccolo)
Training (Roshi, Karin, KamiSama)
Tournament (Jackie Chun, Ten Shin Han, Piccolo Jr.)
Actually, you can combine the "Search for Dragon Balls" with "Defeat the bad guy" because always there were the good guys and bad guys searching for the dragon balls.
And think about it, they made 3 wishes in total
1st. Panties for Oolong (Pilaf Saga)
2nd. Revive Upa's Father (Red Ribbon Saga)
3rd. Revive all the people who were killed by Piccolo (Piccolo Saga)
It's the plot, not character development or story. The main "objectives" or "goals" are the same, the story behind the plot is what makes the difference.