Actually leather armor is still used with metal armor. Lots of armor involved leather base with rings or plates and some armor had plates between leather and all sorts of other examples. The cheapness of leather or of metal and leather vs pure metal made it usable all the way to the high and late middle ages. Furthermore there are also some mobility bonuses to leather and leather/metal armor.

I suppose it depends on the kind of game you are playing. Games of whatever genre with a low number of units on the player's side may be less amenable to the trade offs of different materials.

"Buff Coat" in the early gun age when armor generally couldnt stop the new weapons (guns) sufficiently and maneuverbility increased in importance

crafting can also be a way of raising money (converting raw materials into higher value) selling it and using procedes to obtail somthing your character would never have skill to generate themselves..

In some games it expands the simple 'loot and sell' pattern into "loot/harvest - manufacture-sell" and can give players a few more activities to do (and possibly additional goals to pursue).

This is true, but also the source of half the economic problems associated with crafting in MMOs. If a player can craft enough items for two players to consume, that means only if half of players don't do any crafting will everything break even. If a player can craft enough items for 10 players to consume, that will never balance out because there are always more than 10% of players who wants to craft. In fact, what are you doing spending a bunch of development resources on a crafting system if you expect only 10% of your players to use it? It's nice to allow players to opt out of crafting, but best to design a crafting system that more than 50% of players are going to want to play with (and not do so at a constant loss of money against cutthroat competition).

Many games try to deal with this by allowing players to only craft one type of gear per character. As a player, I don't like this system at all. As a designer it's not bad, but will still fail if paired with gear that is infinitely resellable. You have to add a second factor like "all gear is soulbind on equip" to make sure crafted items regularly leave the economy to make room for new ones. Durability isn't as good in my opinion, but it can accomplish the same effect IF there is no way to repair worn items. Oh, and you can't have gear dropping from monsters left and right, unless it requires some further crafting to make it usable. Overall, a system where one player can mass-produce crafted items is always going to be finicky and difficult to balance.

Last time I put together an MMO design my attempted solution was "crafting tickets". The idea with these is that players can craft as many items for themself as they like, but they are all soulbound to the craftsperson. The only way to make a crafted item saleable to other players is to use up a crafting ticket on it. And these are in short supply, and can themselves be sold in the marketplace, which encourages people to hoard them rather than using them. By short supply I mean each player would get one each level-up, plus a few would be winnable as pvp arena prizes and boss drops. The math should work out that if a player needs a full set of new gear every 5 levels, they should get slightly fewer crafting tickets in 5 levels than needed to make a whole set of gear. This system should theoretically also allow gear to be broken down for ingredients (excluding tickets) without unbalancing the economy. I'm not sure if I'd still go with this system if I were to do a new MMO design today. Actually I might get rid of stat-giving gear altogether.

Links to previous crafting-related threads. I finally had time to look through the archive.

http://www.gamedev.net/topic/627218-crafting-system-what-is-ideal/

http://www.gamedev.net/topic/558234-need-options-on-two-different-crafting-systems/

http://www.gamedev.net/topic/543349-risky-crafting-instead-of-skill-rank-based-crafting/

http://www.gamedev.net/topic/520552-creating-a-fun-simple-yet-complex-crafting-system/

http://www.gamedev.net/topic/512306-crafting-system-for-fantasy-mmorpg/

http://www.gamedev.net/topic/510025-crafting/

http://www.gamedev.net/topic/485174-what-is-fun-about-trading-and-crafting-in-an-mmo/

http://www.gamedev.net/topic/423590-growing-equipment/

http://www.gamedev.net/topic/302459-whats-cool-about-owning-a-house-rpg/

http://www.gamedev.net/topic/544310-mount-system-design/

http://www.gamedev.net/topic/277230-an-analysis-of-mmorpg-item-systems/

You didn't list any of my threads. Although to be fair I can't remember how many I had here as opposed to MMORPG.com. But I had extensive thoughts on how to make good crafting and how to integrate it into the entire game. Crafting is honestly pretty hard. Too many people try to shove crafting into a game that isn't meant to have it. That's probably the biggest problem.

You didn't list any of my threads. Although to be fair I can't remember how many I had here as opposed to MMORPG.com. But I had extensive thoughts on how to make good crafting and how to integrate it into the entire game. Crafting is honestly pretty hard. Too many people try to shove crafting into a game that isn't meant to have it. That's probably the biggest problem.

I was going by thread titles, so if yours didn't have "craft" in the name I may have skipped over them. Also I was trying to get only ones with more than one page of posts.

I did see this one, I would have linked it if it had had more posts:

http://www.gamedev.net/topic/614959-crafting-and-magic-and-skills/

If you want very nice "crafting" engines and reason to crafts:

- Paradox Salem - its crafting MMO, where stuff you can make is based on "perks" that you can buy when skills are enough and you fill the skill bar by using some stuff. You can craft stuff beginning from an axe and finishing with houses and advanced mining machinery.

- WURM Online - another crafting MMO. Here You can craft everything that you have resurces for, and tools to make it, but different crafting skills affect quality of the stuff. So f.e. if you make a compass with high QL it will show north, and with low QL it will show random direction from north-west to north-east. Here you can also craft everything, first you craft parts, than make tools, homes (wall by wall), carts, boats, ships etc.

- Xsyon - You scavenge resources, and make everything from it. Game servers starts as empty regions/forests/lakes, while every building and every piece of equipment in a game is made by players.

- Don't Starve - simple single player game with a lot of crafting. You wake up in a world and need to survive. Gather resources, build camp and machines to research another stuff to craft, and craft it.

Now crafting is in nearly every crafting MMO game, buy usually it works same, and its only "piece" of crafting. Those games above are all about crafting (or craft to survive), so I think they are best to start in your case.