While I was waiting for the games to start, I picked a round at random -- Round 5 - Commentary on Livestream -- and reviewed the video, which I had already watched live. Then I noted all of the comments on the openings which were on a higher level than straight analysis of the moves; let's call them meta-comments.
Ivanchuk - Carlsen: In every round Carlsen's game has been one of the commentators' favorites. In this game we see that they were already unfamiliar with the opening variation on the eighth move. (LT is IM Lawrence Trent, the anchor. NS is GM Nigel Short, guest commentator and former challenger for the World Championship title. The numbers show the time into the clip when the commentators switched to talk about that game.)
LT: 'This is all main line theory.'
LT: 'This is all main line.'
NS: 'I've completely forgotten everything here [...] This is the Karpov - Kasparov stuff'
LT: 'That [move] must be a novelty'
NS: 'I don't know. We need some Gruenfeld experts. I don't know this [move]'
LT: 'It's a rare one. It's certainly not one of the main ones. I'm not a Gruenfeld expert either.'
NS: 'We'll probably find on the database that there were vast numbers of games played, but I'm not very familiar with this at all.'
LT: 'No. We don't use engines here. We don't use databases. We just use our raw talent.'
NS: 'That's why we're struggling.'
LT: 'We get up to move eight in a Gruenfeld and that's about it.'
Kramnik - Aronian: No one ever seems to find much of interest in Kramnik's openings and no one ever seems interested in spending much time on them. He is on too high a level.
[They explain some features of the moves; no meta-comments.]
LT: 'It's dull o-clock'
Grischuk - Radjabov: Just like the Ivanchuk - Carlsen game, neither commentator is familiar with the specific line played.
NS: 'This [move] is quite trendy. God knows what the point of it is. [...] This [other move] is the old stuff and I'm an old-fashioned player. There's nothing wrong with it, but it's very old. That's my sort of chess.'
[After some moves]
LT: 'This has been seen a lot of times as well. [...] Grischuk has only spent a few minutes on this.'
NS: 'I'm sure he's got all of this prepared.'
Svidler - Gelfand: Here we see some real enthusiasm. White played an unexpected move that allowed the commentators' imaginations to roam.
LT: 'Look at this! That's more like it!'
NS: 'Is that a move? You can't do this in the Gruenfeld. That's illegal, isn't it?'
[They discuss the move.]
NS: 'I'm enjoying this.'
To summarize: At an early stage of three games the commentators were unfamiliar with the opening variation played. In one of those games they found it uninteresting. The fourth game they loved because it was unexplored territory.
The commentators are both titled players, one of whom was world class in his heyday. If they can't follow the early stages of the game, what hope is there for keen club players like the rest of us? Then consider the other 600 million players (?!; FIDE's number) who might only have played a few dozen games in their lives. The theory is too deep, the precedents are too wide, and the players' computer preparation is too complex. No one knows what is going on in the game except the two players themselves.
In that last game, GM Short said, 'I'm enjoying this'. At that moment he was on the same level of understanding as at least one of the players, as were the rest of us. This is not to say that everyone understood equally. The players, after all, are among the best in the world with a better understanding of chess than 99.999% of all chess players.
To return to chess960, this is exactly the attraction of Fischer's greatest invention. Everyone -- whether player or commentator or spectator -- is looking at the position for the first time ever, applying their own knowledge of chess to tackle a completely new chess position. Chess might not be a great spectator sport, but chess960 might well be.