Carpentry is the profession for the artisan's artisan. Most of the things that a carpenter makes are focused on improving the quality of life of Norrathian urbanites who rarely venture out into the wilds. Generally speaking, they provide the fuel for the flames of player vanity, producing the majority of furniture available in the game. Each piece of furniture tends to carry a status upkeep reduction on it, so players that load up their house with good furniture can eventually reduce their upkeep costs to nothing. This helps to feed demand for crafted furniture.
Many players only play Everquest 2 to decorate their house. That's where the carpenter comes in - you're providing more options for people who like to decorate and redecorate their virtual abode. Carpenters are also the only tradeskill class that can produce divine altars, which have a great deal of adventuring significance. Players who have an altar in their house dedicated to a particular god can pray to it and make sacrifices, tithes and complete quests for something called favor. Favor can then be spent on blessings, buffs and other "miracles" from your god to help you out in combat. Most of the various spells that cost favor require the player to complete a quest of some sort. Altars make for brisk trade for carpenters, as players covet the favor buffs that they give access to. There are many tiers of altar that give different bonuses.
Otherwise, carpenters concern themselves with producing decorations like chandeliers, chairs, tables, bookcases and just about anything that you can think of that will make a home look attractive. They can also produce mannequins with which players can display their arms and armor. Paintings and tapestries can also be created if you have the recipes for them. The decoration system allows for a stunning level of customization, and the number of recipes available to a carpenter help to ensure that there is still a brisk trade in their items. New housing areas that have been regularly released with almost every expansion also helps to make sure that players are continually getting new houses that they need carpenters to decorate. Some items, like certain statues, provide buffs to artisan skills, making them a very valuable item for artisans looking for a leg up.
In short, carpenters are more about adding to the atmosphere of EQ2 than producing equipment that will specifically help out adventuring. It's a fun and unique tradeskill that can make you a lot of friends. If the idea of being a fantasy interior decorator appeals to you, becoming a carpenter might be a good idea!