If only someone would rethink music notation successfully.
The people that use notation the most, and take it the most seriously, are usually the ones that have invested a ton of time learning to sight read and knowing how to properly express their ideas in it; hence they are almost certainly going to be hesitant about switching to a new format. We musicians tend to be a conservative bunch; after our first few years playing/experimenting, we pretty much solidify what we like and hardly ever deviate from it afterwards.
I (a guitarist) for example, only really play 2 brands of strings, I have already made vast generalizations in my head about what amp/guitar/pedal brands I like and don't like (as opposed to judging on a product-by-product basis like I would for most other things), and I don't see that changing soon. Likewise, once you develop your notation style, it would probably be hard to really think of trying something new when you've just come up with a cool riff and get caught up in the heat of the moment trying to build on it.
Although I can't wait to see the day the next evolution in songwriting starts getting widely adopted, I can't say that what we have now is really that bad. Traditional staff sheet music does makes it easy to 'visualize' what a piece sounds like, and that's a feat that even well notated tablature can sometimes struggle to convey.
As for my startup? We just want musicians to be able to precisely jot down something like this on a moment's whim (fx and all): http://www.youtube.com/watch?v=YU52hGo3nNc
tl;dr I'm not giving up the ability to look at an orchestral score and have a pretty good idea of how it sounds just to learn that skill all over again.
That being said, there are hundreds of years of tradition behind current notation and that kind of momentum is unlikely to change. Guitar players came up with tablature, which is great except for the lack of rhythmic information in the notation.
That said, it is remarkable how easy it is for a pianist to play on sight, whereas for classical guitarists that's usually only a skill you can hope to attain if you major in music. Banjo and ukulele are even harder, because of the re-entrant tunings where your highest note is the topmost one instead of the bottom one, destroying what little correlation there was left between sheet notation and hand/finger position.