Of course this leads to a problem, if each character can only select one crafting skill they will literally find themselves crafting only a few items out of the dozens or hundreds of total items they are capable of crafting and I don’t know about you but I find that rather dull and boring. Personally, I rather be capable of crafting a plethora of different items, that way if or when one market is oversaturated I can fall back on my other tradeskills and craft items that are still in demand. The more diverse I can be in crafting the more engaging it is for me to determine what the market needs are.
The final issue I have with limited crafting is…alts. Now I enjoy making alts because I enjoy trying new classes, different factions, new quests, environment and etc. However, I do not enjoy making an alt for the sole purpose of taking up another craft. Often times a tradeskill needs another tradeskill to make it complete. For example, in Star Wars the Old Republic Cybertech needs Artifice if you wish to continually be able to completely modify all your custom gear. This is because Cybertech is not capable of crafting mod enhancements that are used in just about all customized gear. Therefore, in order for me to completely modify my custom gear I will need both cybertech and artifice, but of course I can only choose one crafting skill. As a result, and technically speaking, cybertech and artifice are tradeskills that are incomplete and not really fun to utilize since i need both tradeskill but can only have one per character. Go figure.
Honestly, I think it's about time mmo developers allowed diversity in crafting. Allow players to pick and choose all crafts available. let us craft goods from other tradeskills anytime without any penalties. If developers allowed this while making the economy more player driven, this will add more diversity to the game. Players can now in a meaningful way become crafters and supporters of pve and pvp. They can be tradesmen with the vision of supplying goods to allies, enemies, and themselves. When you think about it, who wouldn't want this?