If you play the Ironclad mod, learning jump points and their location relative to stations is key to cutting travel times, so I would prefer if Navigation opened more jump locations rather than increasing burn speed. IIRC, Alex has mentioned that jump points can be from one part of a solar system to another, which, IMO, would be a much cooler way of cutting travel times than making the ships all go faster.
Unilaterally going faster doesn't sound like that big a deal, but it has a huge effect on the balance of the rest of the game. Since the game has been, to date, more of a tactical game, it hasn't mattered too much, but as we get into the more strategic parts, Navigation as it is now will make less and less sense.