I would be more excited about a Lytro that would record a second or so of full high speed video (1000fps would be ideal, but it'd probably still be useful with much less), so that you could adjust both the focus and the exposure after the fact. Eliminating the need to take a bunch of photos in a row to get a "good one" would be a legit improvement.
I would be interested in knowing if their tech could ever be phone-sized. It looks like focusing the light correctly on the sensor is more difficult than with a conventional camera ( their promo video looks to show about 8 lens elements). The entire design is basically a big lens with the sensor and screen on the back, that's why they adopted such a strange form factor. That said, there is significant variability in size with traditional camera lenses, so maybe once the market matures someone will figure out a way to produce cheap plastic light-field lenses.
As far as the high-fps goes, they use a standard sensor with custom microlenses. Procuring a new sensor, either for higher resolution or faster frame rates, is probably more expensive and less likely than continued software updates, and maybe even changes to the enclosure and lenses. I suspect sensor acquisition is a significant part of these cameras high price.