I agree, why mess to much in this area? There are dedicated things out there, There are decent 5.1 systems that are cheap. I remember that set Nige Linked some time ago going for £20 reduced price a few of us picked up. I still use that on my pc and it does the job well, not bad sound at all. Replaced some of the speakers with better since though but still. You can get nice ones for not a lot.
LCD tvs are getting slimmer, I think My samsung has pretty good sound really, and the one upstairs does as well. Why mess with the audio when your building a tv to much and you got the licence costs ets if you put anything more stuff in them that will bump up the overall cost they got to sell the tv at.
Even worse is that they have pushed the speakers onto the back in order to keep the surround to a minimum. This is OK for bass, but the highest frequencies tend to get absorbed by the wall.
The speakers are just screwed onto the plastic of the case, which has been happening since the first wood cased sets. Putting any cheapo speaker into a random box isnt good for its sound output. Putting it into the right box can hide its worst qualities and enhance its best.
On the other hand most people dont actually care about sound quality that much, note the number of people still listening to tinny little radios pushing out fm.