If only all other manufacturers forced carriers to allow end-users to get software updates directly
This is under the control of Google/Android, not your phone manufacturer. Google just refuses to organize things that way. It's encouraging that Google has (finally!!) fixed one major problem with Android; they could easily allow direct OS updates as well, if they wanted to.
Android is just another OS, like Windows. Windows updates come from Microsoft; it doesn't matter whether you own a Dell or a HP or whatever, the update comes from Microsoft. (Device drivers may come from nVidia/ATI/etc, but core OS bits come from MS).
Scary thought: does that make Microsoft actually smarter about OS design than Google?