I agree, but chip makers, handset makers, and ultimately carriers do care. Apple, Sony, Microsoft, and Nintendo sure care a great deal about people jailbreaking their devices.
My point was not that a new kernel would directly persuade potential buyers, but I do think it is needed to support the features that users have come to expect from modern phones (i.e. multitasking). In my opinion WP7 is just not up to the task, so if they want to compete, they need to step up their game in the OS department.
"You still haven't answered why Nokia would sign on with another sinking ship rather than simply choosing to make great devices for the leading (free) OS."
I don't know, maybe MS is giving them a truckload of money? Nokia has a large software development group, so maybe the deal is that Nokia will develop apps for WP7? Maybe they just want to differentiate from the Android horde? I really don't know why they would go with MS, if indeed they choose to do so, but all I'm saying is that I don't think Windows Phone is a 'sinking ship'.