In some crappy rule of HDMI HDCP the "analog hole" was plugged badly which meant that many sets can't pass HD audio if the source is HDMI. Some TVs read the rule differently and passed it anyway or paid the fee.
So no. The rush to copy protect has blocked the path. No, there is no technical reason why what you asked for could not have been made.
And before you flame, get over it? The current system can work but there are folk that rail against receivers, optical links or such.
And no. No TV will have a 5.1 amplifier to drive speaker directly for a simple reason. I'm sure you know why.
I read articles saying that cable is on the way out and will be replaced by the streaming services and I can see the logic, but I don't see the equipment. Currently I run DirecTV through a receiver to get surround sound. I have a Roku to access the streaming services. I see ads for smart tv's and the new receivers are starting to show a new version of Dolby surround sound, but I don't see devices that do everything you'd want in a world of streaming media without cable. TV's tend not to have audio out with the full surround sound signal. Receivers build in streaming audio services but I haven't seen any incorporating the receiving video services. Will we see TVs that build in a proper amplifier and inputs for a full set of speakers or receivers that handle streaming video and include a hard disk or will computers replace receivers. Am I missing something that's out there now or coming soon that will turn a signal on the internet into a full home theater experience?