I don't think I've been the target audience since about 1985. That said, every now and then a gem still goes by.
Over time I've bought various settings - FR (twice), Birthright, Greyhawk, etc. - but other than the original FR I've never got all that much use of them. I've also got a fair amount of setting-expansion material e.g. some Mystara Gazetteers, some FR stuff, etc.; and for me personally I'm getting it to read - and mine for ideas - rather than to directly use in play. Ergo, it has to be engagingly readable or it's not much use.
Adventure books and modules, on the other hand, have to be exactly readable enough to be useful, and that's it. Function over form. Give me the info I need in a concise, organized, point-form manner that makes the most efficient use of space. Give me detached or removable maps so I can look at the map and read the text at the same time, i.e. no page-flipping; and whie you're at it make sure the maps and the write-ups agree with each other. And don't give me a pile of info I don't need, which usually includes 99% of the backstory stuff they insist on including.