Why didn't MS wait for Intel Broadwell for the Surface 3?

While the Surface 3 seems to be an improvement over it's predecessor I can not understand the logic of launching a new generation product with last year's architecture (Haswell). I know the newer Surface 3 is using the 4300U vs 4200U but that is a very marginal spec bump.

With Broadwell only a few months away, why not wait and launch SP3 in September? Which brings me to the next question - What happens when broadwell comes out? Will the SP3 just get a processor bump? If so, then again you have a bunch of early adopters who will feel shafted and will have regrets about buying a new product with an older processor.