Sword of Spirit
Legend
Sure, Dark Sun and Planescape might be more appealing than, say, Dragonlance, but, again, that's just a RELATIVE standing.
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Same goes for a lot of these settings and whatnot. It's all confirmation bias where folks that want a particular ruleset REALLY want it and just can't fathom that what they want isn't actually all that popular.
Relative standing is all the poll really can tell us. But that's also extremely relevant to the issue at hand. What sorts of information do you think could be relevant from a poll that allows you to choose 3 products from 23 options? I'm not sure what standards of significance could possibly be met in such a poll that you think have not been met (other than sample size, which no ENWorld poll hits satisfactory numbers on; with 170 results, this one is actually doing well here).
Of the 23 choices, the mean result is 12.7%, which is almost exactly where Dragonlance falls. The top 5 results are:
1) Planescape/Manual of the Planes (33.5%)
2) Dark Sun (32.9%)
3) Other (32.4%)
4) Psionics (25.9%)
5) Greyhawk (18.2%)
The poll has some issues, including that some people appear to have voted for more than 3 options (the numbers don't add up completely), the presence of a broad Other category is probably better left out of it, and the different treatment of some settings makes it hard to determine popularity of certain things. (For instance, it's more difficult to tell how popular FR is for more content than Mystara because we can't tell if the same people are voting for all three FR categories, or different people are voting for different categories.)
However, with what the poll does give us, it shows us that psionically-dependent Dark Sun was the second most desired option (and only 1 vote less than the first option). Psionics was the 4th option and clocks in at double the mean result, falling right behind the incredibly broad and generally popular "Other" option, and being more than 40% more popular than the option behind it.
As far as I can tell, within the limits of the poll, it demonstrates that Psionics are very high on the list of official content priorities for respondents.