Who cares if they update the os kernel to the latest version? Are you joking? No it doesn't really change anything for the end user, so they might as well revert back 3 kernels of darwin? Are you serious in saying it doesn't benefit the end user? Jesus Christ.
To say it runs faster than lion, isn't really a compliment, seeing as lion was dirt slow, slower than the linuxes, much slower than windows 7. As far as older systems go, which ones are you talking about? The ones apple is force obsoleting? And we shall see how faster it is than lion, when the proper stats about this come out after release.
It's not a mere $20, it's a billion dollars for apple, for a service pack, that a lot of us are forced to upgrade to because lion was such a poor release to begin with.
Ok, so what does the version of Darwin in iOS 6 have that this version doesn't, that makes it so much better?
It was slow yes. For me, older system means 2007 iMac, 2.4 GHz Core 2 Duo, with 2GBs of RAM. It's almost as fast as Snow Leopard for me. If you have a preffered method of testing speed, I still have a Snow Leopard partition (and Lion, and even Windows 8) and I will gladly test it for you.
It's a mere $20 for users. What difference does it make what Apple makes? Everyone is well aware of the price Apple charges. This is no different. Are you saying that Apple developers should work for free? Not charge for a years worth of work by hundreds of developers?