She has an appearance beyond a cameo, actually. As I mentioned, she appears living with Tienshinhan and the Z warriors meet her when Krilin and the others go there to get him for the battle. Later, she appears in the Kame House, readying a weapon for the battle just as Vegeta and Nappa are about to arrive (I recall she's readying her weapon as Roshi is cleaning the hairs on his nose; in my country that scene was seen).
Proving my point making her small. Does she play a big role to the sagas? Making appearances doesn't make you apart of a story. As I stated before She has no pivotal in dragon ball z but in dragon ball she's more important. She makes appearances time to time but THAT doesn't make her important
Lot of characters just vanished from a saga to the other. However, there was something on Launch's appearance: The other warriors kinda had to struggle with her (Bad Launch) to be able to bring Tienshinhan and Chaos. They made her change to the Good Launch and she left them take Tien and Chaos to the fight. It was, I think, one of the episodes that got off the Kai circulation.
Okay... Characters Vanish... Vanishing doesn't make you NOT important but multiple appearances make you important. Launch was neither of those things she was gone most of the time and made rare appearances She's only significant to dragonball