You are kind of doing the same thing here - you're giving up the incredible advances in visual technology because of some of the secondary advantages... some of which you can still get with a modern TV.
I have a Big Flat TV(tm). Yeah, takes a couple of seconds to turn on. Big deal. It has no smart functionality - and yes, there's a media center PC plugged into it (sometimes that's a Raspberry PI, but those are a bit unresponsive).
As for the sound - no way will I let the TV handle the audio. Audio goes to the AV receiver and to real speakers. It did that even when the TV was a bigass CRT, because no TV has 5.1 surround.
Did I make some sacrifices? Maybe. But the whole point of a TV is to have pretty pictures. If you don't think hidef is worth some minor sacrifices (which, as stated, you can mostly work around) then i's pretty obviously not an important medium for you... and you are definitely in the minority.
And even you aren't claiming that the picture quality is better than hidef.
(BTW I use a plasma TV, so blacks are still blacks).