I can understand the idea, and it would definitely work in an otherwise too-predictable game where luck could be a good way to mix up the gameplay. Juice Galaxy, however, by its signature floppiness, already 'mixes it up' with the sheer floppiness; the on-screen mechanics of how things move, in and of themselves, make unpredictability, the the countering of which with skill is the exception instead of the norm.
I will, however, say this: Tying in with the forum subject we're on now, one of the "perks"- or possibly more than one- afore-suggested could be increased bonus in the case of particularly successful, optimal uses of the momentum. I for one would love for non-combat gameplay to be explored, but if one were particularly eager for crits, the current bread and butter could be given damage boosts for when the player gets the momentum just right.