For some reason some people regard separated bicycle lanes & paths as an opportunity to drift off into obliviousness. If a tree falls across a bicycle lane, will anybody stop? Just because you're not quite as exposed to bad interactions with motor vehicles doesn't mean you can go to sleep.
I suspect it is just a bad habit manifesting in a worse situation. Cyclists are bad about stopping for crosswalks. When I drive, I stop for a crosswalk if any pedestrian is anywhere near it, and wait until it is completely clear before proceeding. When I cycle, I don't think twice about rolling (at a slower speed) through a crosswalk while a pedestrian is well on the other side of the street but still in the crosswalk. I think this is pretty common, and while technically wrong, not really a big deal.
In the separated bike path the space is pretty restricted. There isn't room for both a pedestrian and a bike at the same time, and the bikes really need to stop. They can't just "dodge" the pedestrians. Most of the cyclists will figure that out real quickly and change their habit and stop trying to roll through, and a few simply won't (just like some cars).