Blueprints for things like guns, bows, swords, etc all have damage % modifiers listed on them. If you put levels into your crafting skill, you can boost those percentages even farther. You can also increase the effectiveness of recipes you cook with a boosted crafting skill.
It takes a lot of levels into crafting to see a significantly better chance at a boost so that's why people make alternate characters with every level in crafting, add them to their tribe, and log in with that character just to craft things.