Frank Kogan

Well, one point they make in the Science piece is that they believe that they are actually underestimating the effect of social influence:

Our experiment is clearly unlike real cultural markets in a number of respects. For example, we expect that social influence in the real world - where marketing, product placement, critical acclaim, and media attention all play important roles - is far stronger than in our experiment. We also suspect that the effects of social influence were further diminished by the relatively small number of songs, and by our requirements (which aided control) that subjects could participate only once and could not share opinions. Although these differences limit the immediate relevance of our experiment to real-world cultural markets, our findings nevertheless suggest that social influence exerts an important but counterintuitive effect on cultural market formation, generating collective behavior that is reminiscent of (but not identical to) "information cascades" in sequences of individuals making binary choices.

So what they're showing is that even when social influence is limited, it has an enormous effect, leading towards extreme results and limited predictability. Any of the other social effects we factor in will just increase the unpredictability.

One potential lesson from this experiment might be, "It's best to go with the tried and true even though you know it won't always work," and this is where some of the conditions you're bringing up might act as a counterweight. The point being that the untried have a shot, but which of the untried do well is also unpredictable, owing to social influence, but when something does do well it will seem to explode out of nowhere. (He mentions Harry Potter in his NY Times piece; it had been turned down by eight publishers.)