Okay, I know this has been brought up before, but...

Rand, one thing that really bugged me in DS3A was not only the lack of documentation, but also the fact that it was a WIKI.
That's no way to do documentation, sorry.
I want help files. Searchable, well written, help files I can access from within the application. Or at the very least a PDF manual.
Without them your users are simply stuffed if their connection drops, or they are on dialup, or need to work offline for other reasons.
Many here have (3D work) machines that are not connected to the net. Others work for companies who will block access to many sites they don't deem work related. (FWIW -- mine blocks Daz3D, Rendo, RDNA and a few others.)
Online documentation is not a good thing, and a wiki is too easily messed up if you're not careful.

So... no to a documentation wiki.

Another that was brought up, more generally, is the ever-present dissatisfaction with promo shots.
Something needs to be done about this.
A hair figure needs shots from the front, both sides, and the back. It needs to have enough space at the top not to cut off the crown of the head so you can see the whole figure. Hair promos are my biggest source of frustration on the Daz site.
I don't care about "Artistic renders" showing every morph the hair can do -- if it lacks the basics, I won't buy it. I got burned too many times.
Many, many hair product shots are severely lacking in actual informational detail. You have 29 shimmering colors? Cool. I don't need to have an individual render for every single one -- all from the same angle. If you don't show me what the un-posed, default hair looks like from the front, back and both sides, then I'm not going there.
The crown-cut-off is just as bad. I've seen hairs where it was so "artistically" rendered/cut, it hid the wisp of hair sticking out on top. To me, that is on par with misleading the customer. No sale -- or often a return.

Clothing often falls foul of the same "artistic" hide-and-seek tactics. And then there is that M4 hipshot pose. Can we get rid of that horrible pose, please? Every other product that shows up uses that godawful pose to show off clothing "in it's best light". Newsflash -- I'd say 90% of your customer base loathe that pose and are turned off by it.
Maybe create a set of "PA/Promo Shot" poses that are mandatory to use as default "Front/Back/Sides" shots, and make them as natural as you can? If the creator wants to be "artistic", fine. But the default "Show off" images could be a bit more streamlined.

Shoes. If there are shoes with a clothing item, they need to be shown, not the feet cut off to show how nice the shirt is. You have no idea how annoying that is. I don't want to have to go into the forum to ask for someone to post a render of something. When I have to do that, it means you just lost an impulse buy.

The popup promo window...often loses the scrollbar once you click on the first image in the list. Annoying as hell. I have a big screen, but I was recently wrestling with a Stonemason preview that extended way down the bottom and I could not get to the bottom image without relaunching the promo preview popup. (Happens on IE and Firefox, as well as Chrome.)

Those are my promo pet peeves. The other is that I have to guess which items are used in a promo shot, if it isn't a Daz product. It wouldn't hurt to list what it is, even if you don't have a link there because it is not one of your items. At least we would stand a chance of finding it by searching. Let's face it, we only go in the forum and ask either people there, or the PA direct, and they'll tell us. It's not like it's a state secret. (Just look at the amount of "Which hair is this?" threads.)
It could be made a lot clearer what has been used, and I'm sure many people would really appreciate the effort.

But yeah...promos are an eternal bugbear with me. :) (And many others.)

Silke