Yes, I have played D&D (What on earth would make you think I haven't?) - and that tremendous evolution is _exactly my point_. It's not the same today as it was when I started playing in 1980, let alone when it originally came out in 1974. There's new character classes, new races, new systems, deep changes to existing systems, etc... etc... Original D&D is virtually unplayable by modern standards, as there's simply too much missing that has become de facto standard in RPG's since it was published. (Under the gloss of fantasy, it's DNA as a medieval miniature figures wargame shows clearly. They're still there too, though deeply buried and virtually invisible to the casual eye, even today.)You obviously never played D&D
Actually, in 1974 the entire D&D game came in a little box with a couple of soft-cover manuals. The game has evolved tremendously over the years. From the original 'basic' set, to Advanced D&D, to 2nd edition to 3rd edition to 4th edition, Tons of books have been published over the years. Monster manuals, maps, player manuals, dungeon master manuals etc.. Countless dungeon modules have been created over the decades as well. Not to mention the ability of DM's and players to create their own dungeons.
Chess on the other hand has remained more or less stable for two centuries (and the first and still recognizable and playable codification dates to the 13th century), and the codified international game is nearing it's century mark. The rules of chess evolve slowly in response to evolutions in gameplay. The rules of D&D evolve in response to gameplay, the whims of the developers, fashion, market forces, and whenever the publisher needs an infusion of cash - as do those of UO. (And they must do so in order to compete in the marketplace - a battle chess doesn't even bother to try and fight (because it appeals to a different demographic) and one which UO is slowly and seemingly irreversibly losing.)
Instability and the constant need to appease the market and maintain cash flow does not bode well for longevity.