My original concept for this was to create something that could either be played as a chill drawing program, or an infinite idle/clicker game. To that end, I didn't really want to add an incentive to unlock everything or bounce the balls faster, other than the intrinsic motivation to see the next ball. I only had time to add a few balls though, so it does become "pointless" pretty fast.
In the game's current state, I'd consider adding some indicator that everything is unlocked (say, a star appearing next to the title) to say "you did everything, so you can stop now if you want"