Per their site, Pebble's current product line has three different case designs, each available in at least three different finishes, and one with an additional heart rate monitor. That seems like an awful lot of SKUs for a small hardware startup to develop, manufacture, stock, fulfill and support. Their latest kickstarter added even more models.
From my armchair, it looks like they tried to expand and segment their market too quickly, for the sake of both growth and the optics of their product line in comparison to Apple.
I'm in the early stages of creating the world's tiniest "hardware startup" (the product consists of a single piece of metal), and it's a constant discipline to not get caught up in offering variations on the base design. Every product design choice ripples through the supply chain, increasing complexity and overhead at your peril.
Good luck to all the folks at Pebble in their new endeavors.