Most people don't use headsets on large panels, which is what variable audio outputs are usually used for. Partly because the headphones would need very long cables to reach the back + the distance of sitting back quite a distance from a large screen, and partly because most people use an amplified receiver these days. Any audiophile worth his salt wouldn't recommend using variable audio with a receiver. Sending a "too amplified" signal could damage some receivers, or cause distortion.
But on one point, I agree with you - if this is a deciding factor to being happy (or not) with a TV, then consider all your options. We don't have variable control on our audio outs. That's not been a secret - as you correctly noted - for years. It's not "beyond comprehension", however, because there are logical reasons why variable isn't on a large screen TV, and I hope some of that was addressed here. Those are logical reasons the feature wouldn't be added.
Also, not all models of Sony have variable audio, and LG doesn't advertise it either way. I understand that this situation angers you somehow, and I'm sorry you're not happy. But before we encourage everyone to run and jump in the competitors' pools, let's make sure there's water before someone picks up a Sony KDL-32BX330 or a KDL-55BX520 thinking it has more than the same "fixed" audio feature. I looked on their site, and they advertise both of those sets as "fixed" audio options.
I'll be happy to escalate your post and opinions to the decision-makers, but it's not uncommon for that feature to be absent in today's televisions.
Though we may disagree, I hope perhaps this at least gives you some perspective from a different point of view.
In this day and age it is beyond comprehension that all Samsung HDTVs still do NOT have any way to control external volume from the TV or TV remote??
Especially given the crappy nature of their built-in speakers. This issue has been complained about on their own forums since 2008 and STILL their TVs are produced with no way to use directly connected powered external speakers.
The solution? Buy LG or Sony - they get it. And all their TVs have variable audio out ports.