This pretty much sums up the problem with Dragon Ball's power creep. Destroying a planet means nothing at this point, destroying exactly half of one is a more impressive feat than destroying the whole thing.
The point wasn't about the demonstration of power, it was about his arbitrary nature and complete indifference to destroying a planet. Freiza and Cell only considered it when they were pushed past their limits, their first instinct was to just brutalize and subjugate the populations. We've had planet busters since late Dragon Ball when the moon was destroyed, its more about the character's mindset in this scene.
