Why don't people take Apple to task for doing the same thing? You can't take an iPad and install Linux on it, or Windows for ARM. You're locked into running iOS. Apple doesn't even allow downgrading iOS.
Same with Android devices that come with a locked bootloader. You can't install anything other OS version/flavour than what the manufacturer dictates.
Yes, it's unfortunate that Microsoft has this policy, but why is it that people only complain loudly about locked bootloaders when it comes to Microsoft products?
Apply the same standard to Apple and Android products with locked bootloaders. Microsoft isn't the first one to do this, and they won't ship nearly as many devices as other manufacturers who lock down the boot process.