The CPU is not socketed/replacable because intel simply does not sell socketed laptop CPUs. If there was a socketed alternative, I'm sure it would be in the framework.
Wouldn't it be nice if there just 'CPUs', and you could pick whatever was appropriate for your desktop or laptop. Sure some would maybe only make sense in one package, but there must be some considerable overlap. I use my desktop for work because it has upgradeable RAM and I needed to do that, not because it has a beefier CPU than is available in a laptop.