There is no reason why operating system and user space upgrades need to be tied to the manufacturer. None.
This situation is Google's fault and no one else's.
You have no idea how Android, the Linux kernel, or open source software works. I guess that's why you're hiding behind AC.
Each manufacturer is akin to a different distro of Linux. You in fact do have to wait for Fedora or Ubuntu to update their packages before you can apt-get them. You don't get them immediately. Nobody can force them to hurry up. Not Google, not you. They control the keys to apt-get.
This is because Fedora/Ubuntu/etc can modify the kernel source and the source of any package that goes into their system. They also have to make sure they all work together. Nobody else can do it for them because they don't know what changes they've made or how a change will impact the system as a whole.
Samsung maintains their own distro of Android. They control the kernel source. They control the packages included. They make a LOT of changes to the system. Only Samsung can update the packages they use and only Samsung can push out an update. Nobody can do it for them even if they wanted to.