Raph has an interesting post up that made me think.
In most games of all types, the enemies are faceless bundles of statistics, save for bosses. Similarly, the player upgrades by buying the next generic bundle of statistics, whether it's a new gun or a nifty wizard cloak.
I've played every Elder Scrolls game that's been made. You know what the biggest rush in those games is for me? The slew of random crap you pull off of every corpse and out of every treasure chest. The idea that you'll find a dagger with a few new capabilities, or a left bracer with a funky new graphic, or a loincloth of burning.
When I play those games, I'm totally addicted for ten, fifteen hours. Then I lose all interest. Why? Because the loot doesn't hold up. By the end of those hours, I've explored everything the game has to offer, at least as far as I'm concerned. The first weapon I find that does blammies when I stab someone? What an incredible rush. The next one? Not so much. The seventh one? Not at all.
It devolves: the only thing that interests me is the graphics associated with the items. A fruit-filled hat is worth more than the flamey sword of Nimbulus, because the flamey sword is just an extra +5 to something... but the bananahat is unique. Plus, I can enchant it to be a fruity hat of flaming, if I really need the flame.
Of course, a steady progression of "unique" is required there, too. The bananahat only holds my attention for so long before I must move on to the next hat.
Actually, that's a failure on the designer's part. The problem is that there isn't really enough feedback to prolong my joy in my bananahat. If everyone commented on my bananahat and changed their interactions with me in some interesting way, the bananahat would become extremely interesting to me. Also, generally speaking, there isn't much in-world feedback.
You might be able to see yourself, but it's a rear view and the costumes aren't generally very interesting from the back. Notice that the new "custom-avatar chats" always show your character from the front, even when they're full 3D? Yeah, fronts are better in terms of feedback.
Worse, the costumes themselves leave only a small mark on the screen, especially in Elder Scrolls games. World of Warcraft got this right: the costumes are extremely loud and large, totally dominating your character's appearance. Of course, there's the problem that you have fewer pieces to play with, and that's a big drawback...
Moreover, there's only so much joy you can get from permutations on the same stock. No matter how many hats I wear, they all go on top of the same head, with the same art style and the same model. The base gets boring, even if the hats don't, and that drags the hats down. Don't get the hats down!
This is true even in games like SecondLife. It doesn't matter that there are 50,000 different kinds of "hats" and more coming out every day. The stock beneath is the same, so they stop being interesting after a while. Thus the thriving business in morphing your avatar: you can't really wear clothes, but in changing the baseline you have changed your whole... um... baseline.
Okay, as per my recent unfortunate habit, I've started to ramble. What I'm saying is:
Manufactured or unique is the wrong question to ask. Randomly generating 500,000 different kinds of sword will only broaden the game so much. In the beginning, it'll be awesome, but by midgame, you'll be just as bored of the random swords as you would be of 100 carefully scripted, balanced swords. You'll know the parameters. Random generation is really a "wide" solution rather than a "deep" solution, and unless you plan on absurdly restricted access to randomly generated things, it's not going to add play depth for anyone other than newbs.
Subtracting out the gameplay elements actually deepens the play, because now the system follows supply and demand. Nobody cares that there's only three blue swords of cystic fibrosis, because they're worse than the ten thousand red swords of blammifying. But if all swords are equal, the rarity of those blue swords makes them incredibly valuable. The same idea applies for hats.
The feedback you get on your non-combat-related equipment is pretty strong in a MMORPG, although exceedingly weak in a one-player game. This means that you don't require as much depth in a MMORPG, because feedback will create more depth. In a one-player game, you'll need to go further. Much further.
For example, being able to dress a whole roster of characters in whatever fashions you prefer. Again: linking these things to play bonuses is basically a bad idea, because it dramatically limits the player's options.
Another idea is to be able to change your avatar, either piece by piece or in whole. You could pull a Shiny trick from Messiah: let the player inhabit whatever randomly generated NPC they can lure into a dark corner alone. NPCs can have some immediate gameplay results (such as being better warriors, or having access to certain places), but in the long run have fundamentally interchangeable capabilities. NPCs should look dramatically varied - it might be best to use animal-people, since they look very different from each other. Elves vs dwarves is about the minimum.
This would allow the player to grab an avatar, equip it, and run around. If he or she wants, he or she can jump into a new NPC - one that looks very different and people react to in very different ways.
This allows them to change the baseline and all the stuff on top. That's cool. I think that would be a fun game, either one-player or massively multiplayer. Imagine the economy that would spring up in body sales. Some NPCs are extremely hard to get because they are always surrounded by people, and those call in the highest prices.
Obviously, there would need to be some, I dunno, GAME involved at some point. But, pshaw, that's the easy part.