We have at least 2 more years before the block size limit actually starts mattering on a significant scale:
https://blockchain.info/charts/avg-block-size?timespan=all&showDataPoints=false&daysAverageString=1The moving average for this years block size has been about 0.4 - 0.44 MBs.
So Gavin couldn't negotiate with the core devs any longer and had to get his coin out ASAP because... why?
The fact that he is backed by a throng of finance industry CEOs diminishes merit from his arguments. We don't care what the already-rich think. Bitcoin isn't for them.