So let me get this straight. The ATV 4k doesn't bitstream audio. Rather than send unaltered audio to the receiver to then be decoded in it's ram and sent to speakers, it instead decodes the audio in it's own ram, then sends to the receiver as lossless PCM. Pardon my ignorance, but what is the difference? A compressed format like DD(+) needs to be uncompressed some where, by some one. The ATV isn't altering or (re)compressing the audio, it's sending an uncompressed lossless stream via PCM, correct?
I mean it's no different from me sending you a zip file, but when you download it, Safari decides to uncompress the zip for you, rather than you having to click on it to uncompress it yourself. It has to be uncompressed some where along the line, it's just a matter of who does it.
This isn't true of HD formats, I know, but we're not even talking about those at this point as the ATV is focused on streaming rather than local media. It's not a Blu-ray player. It's a device to sell iTunes content. And iTunes content doesn't have HD audio. Even the big push for tv content in ATV is only stereo sound. Perhaps in the future Atmos will start to take off in the streaming world and we'll get Atmos support, but you have to realize what you're buying and what its goal is.