The first thing you need to understand when I talk about equipment breakage is that I’m not talking about destroying all of your rare and difficult to acquire equipment.
Or I suppose I am, just not in the same sense that you have come to understand “rare and difficult to acquire” relative to a game like Warcraft. If one boss drops three items for 25 people each week, it’s not very good game design to destroy that item a few hours later.
Now let me ask, should the "challenge" in acquiring a difficult or rare item be in "winning the roll" or in fighting the boss itself? In Warcraft, many boss fights are trivialized and the challenge itself is in the "roll" and not the "boss". As evidenced by the fact that many raiders will kill the same boss 25+ times before getting that Best In Slot item.
But what if each player got their own loot table and item for each boss. One drop every boss for each player involved in the raid. Instead of a 13 boss dungeon that provides 1 drop for each player, you have a 13 boss dungeon that provides 13 drops for each player.
Suddenly, an item that “breaks” after several hours of play is not such a huge obstacle.
Rarity is a relative term. You can make things difficult to acquire by making the boss fights themselves more difficult and challenging. And since the items themselves don't "last" or persist forever, getting that +1 upgrade doesn’t mean you throw out your old sword.
The advantage of such a system is that you don’t need “Gear Resets” to create equality. By virtue of simply playing the game, the content can be tuned so equipment simply wears out over time.
The consistent and constant loss of equipment created by breakage also provides a lot of value to your crafting system and economy. Why? Because the consumption creates a loss that needs to be replaced. An economy only works if that which is being used is consumed.