As for what I imagine it means, I simply don't expect we'll ever get top down design done for cultures, or at least aspects of cultures, that aren't featured prominently in Western media.
I guess the place I'm going with this is that there are problems with actually doing "top down" design on other real-world cultures beyond the purely mercenary motive. Take the Native American example -- you can't do a top down design for that culture, point-blank, because all the most "resonant" tropes are also the most racist. If anything but a complete top-down approach only counts as "aesthetic" then yeah, there's just no way to reference that culture.
Or take Kamigawa. The biggest issue with the top-down design here is that far and away the most prominent element -- the spirit war -- draws on an aspect of tradition and mythology that's
extremely unfamiliar to Americans, and in a way that was actively difficult to parse for people reading and looking at cards. Other stuff was unfamiliar, but Tamiyo demonstrates how something like Moonfolk can succeed even if initially familiar -- it just needs an easy name and visual attached, and a clear theme that people can understand just from the cards. If you try to do a setting like this from the absolute top-down, you have to fill every setting element in from that top-down process, and you're gonna wind up with more spirits than moonfolk in the process.
I don't think anything about their market research keeps them from doing what they've done on some sets in the past, though: attaching a cultural aesthetic to a bottom-up design, then doing a second top-down pass to give that cultural element more heft. After the feedback from Kaladesh I expect them to give that approach a more serious thought in the future.
I'm not talking about that article. I'm talking about the fact that people were suggesting they should ban Smuggler's Copter/Marvel/Ishkanah/etc. But they aren't going to ban anything, because of course they aren't going to ban anything.
What kind of bans do you think would actually have a positive effect? I don't think a big 5+ card shotgun approach would actually have a good effect given the current nature of the format.