I'm really starting to hate this mentality of "My character has to be center stage at all times!" that I'm seeing in this discussion. First of all, no, nobody's character has to be constantly getting the spotlight. It is entirely possible (better even) for characters to trade off who gets the spotlight and when. Yeah, obviously the characters dying in the effort to kill Raditz are getting a little more spotlight right now. But that's right now. There's no telling how the fight against Nappa and Vegeta will go. Other characters who didn't shine when fighting Raditz could very well shine and be instrumental in the defeat of Nappa and Vegeta later. Hell, the show itself proves this to be true with Krillin. Krillin played no role whatsoever against Raditz, but ended up being instrumental in helping Goku defeat Vegeta, and even more so while he and Gohan were stuggling alone on Planet Namek.
Now if you want to argue that there's too many player characters and not enough villains to go around, then sure, I can see that argument being made. Now here is my suggestion for that argument.
Movie Villains.
No really, just use movie villains. Want to have a few more storylines happening in between the main arcs to give more characters more chances to shine? Throw in the villains and plots from various movies. Have Turles show up while we're trying to prepare for Nappa and Vegeta to arrive. Want Frieza to be more of a threat? Throw Cooler into the mix. Reinvent the Namek Arc to revolve around Frieza and Cooler effectively at war with each other for the Dragon Balls while our guys are caught in the middle of it. Or just have Cooler come to Earth some time after we beat Frieza looking for revenge. Write in Lord Slug, Android 13, the list goes on. For God's sake, Kami's Lookout has the freaking PENDULUM ROOM. Have whoever survives Raditz use that room for training, getting beaten down and humbled by whatever foe Mr. Popo has them face, only to have them win a rematch fight later on to demonstrate the fruits of their training.
@Weird Tales The only reason I don't think outnumbering enemies is viable is Bardock. If what you say about overwhelming foes with numbers is true, then Bardock would have never gotten anywhere as close to Frieza as he did. Also, Frieza's 1,000 man army would have wrecked everyone in Resurrection F.