To weigh in on the suggestions regarding obstacles, I actually quite like how they work- the game kind of plays like the water section of frogger. I do also think a bit of urgency would add to the experience, though.
Making obstacles lethal and reducing the count is one way, but I think that would remove a layer of depth: at the minute, there can be interesting choices to be made regarding flying through obstacles to reach a bunch of clouds on the other side, which makes navigating the area quite interesting.
Perhaps adding a third game object that is rarer but lethal would be a good solution? You could have a warning appear at the top, and have a red object fly down quickly, perhaps. Or even just making the natural rate at which the player falls might make things a little more tense.
In any case, if you decide to keep working on the game after the voting period, upping the danger is definitely a good way to go :)