I do not believe that restricting the items that a character can make is a good idea. Firstly, if you restrict the types of items that you can craft, based on levels, you will find a good number of people grinding to get their levels higher. This will happen, just look at what some of the elven farmers, including me, would do in Aluson. We would grind on the low levels crops, such as wheat, and would only log on to collect them to get more levels. Then we would move on to the higher levels crops, like melons. This would also usually prevent people from having multiple different characters. For example, a dwarven blacksmith and an elven farmer. Both require at least two sets of skills, if not more. Without class restricitions, this would be possible. Otherwise, it would never work.