Heh, good point, USB 2.0 would absolutely suffice. You'd hardly need more than a standard audio profile either. Some TVs even support this already - recent Samsung models at least.
A specialized port could theoretically have a lower BOM cost through simpler silicon or port design, but USB 2.0 is free at this point so why bother.
> Personally I use regular TOSLINK to a stereo amplifier and accept having another remote.
The problem with TOSLINK is not only the remote scenario (which I do think is absolutely a necessary feature for any kind of adoption), but also lack of bandwidth for uncompressed surround sound.
Large surround setups at home are uncommon these days, but soundbars with virtual surround is common, and some of us still manage to squeeze in a simple 5.1 setup.
