It would certainly be nice to have this, but just to clarify, kernel source, bootloader issues, and custom recoveries are all separate, and not always related issues. I think I saw earlier in this thread where you managed to get a custom recovery loaded, but couldn't access the partitions. Not sure kernel source will solve that.
From a more deeper development perspective, even with an unlocked bootloader, and custom kernels, without source code for the interface between the MCU and the various system apps (radio, media player, etc), we will have difficulty do much more than themeing/tweaking the system apps.
and BTW, it's not the Android License that requires source. Android is published under a modified apache license. It's not viral. You can close source your code at any time. the GNU license by which the linux kernel is used is viral and requires source code distribution.
Sorry if I'm coming across as 'that guy'. Don't mean to