Flash, not substance

The mainstream rpg market, the one dominated by games like Paizo's Pathfinder and WotC's D&D, has changed a lot from the roots of the hobby. Where once most gamers would have been content with a photocopied manual made in their local library and purchased through the mail, the format of the books has become of greater and greater import to the people buying them. We want books that look good and have lots of pictures, presumably because our imaginations are no longer working on overtime, so we need to have illustrations on every page to remind us what our own particular fantasy worlds look like.

This is really an aspect of the DIY problem spilling over into book design. D&D, like most modern well-known and mainstream pnp games, isn't about coming up with your own stuff anymore but rather purchasing stuff that you find in a store. The shiny pages, the full-page artwork, and the strange layouts are themselves a selling point now with the content taking second place. The encyclopedic style of late-stage TSR  has been supplanted by a very simple and easy-to-read method of writing.

As the writing of the books has gotten less complex their layouts have taken up the slack. They are now shining examples of overdesign. Yes indeed! I said it once and I'll say it again! They have less content and more glamor than any books that came before them. Paizo is perhaps slightly less guilty of this (their Pathfinder book is as gigantic a paperweight as I've ever seen and I confess that I couldn't be bothered to read it thoroughly as I despise 3.x in all its incarnations) but WotC has taken this design schema to heart and so have many lesser companies following WotC's wagon train.