Honestly, it's not worth it most of the time as an attack. A distraction at best. Vegeta's found a full on blast of ki works better now days rather than playing cat and mouse with numerous ki spheres. But it's something he's kept up with, just in case it may become handy one day again.

"They are low enough ki to not do damage." He's not doing this to damage Yondu's weapon, just to give him a new target that he himself doesn't control, and can't be destroyed. And can be taken up a level, once Yondu got warmed up. But not right now, let him get his eye in for them before Vegeta starts making them moving targets.