Transcoding needn't necessarily add much to the cost of a box; there's a Dolby design, for example, intended for specifically this application, which can do the whole lot at - so Dolby says - a lower licensing cost than the individual components.
And it appears that some of the boxes have that design, or something similar; since the test was published, for example, Humax has confirmed to me that a firmware update for their box will add transcoding from HE-AAC. I would hope that quite a few of the boxes out there will be able to do this too, though we shall have to wait and see the response of the manufacturers.
If you have an AV system that supports multi-channel audio via HDMI, then again you should be able to get surround out of these units.
If every single programme on the HD channels actually used surround sound, and I felt that the majority of people would be connecting to a surround system, I'd have attached more weighting to the issue, and that would have altered the scores somewhat.
But as things stand, a lot of what's being broadcast right now is still only in stereo - I had to wait until appropriate programmes appeared on BBC HD to check the functionality of each box. And many people will be looking at some of those other features too, just as much as sound.
It's certainly an important issue - I'd have glossed over it if I didn't think so - but at the moment, may not affect a huge number of people. The awards are calculated based on scores, and those boxes that scored highest did so because of their other functionality, or ease of use.