The answer is no.
Blacksmithing, like Crafting, are optional extras you can choose to pursue but the game will not be any tougher because you lack them. Since Jahan begins with Scientist, and thus a free point in Blacksmith and Crafting, he can repair your weapons for you as well meaning you are free to completely and passionately ignore it...
unless you want to have fun doing it.
Acutally the game is a lot tougher without crafting. Blacksmithing is not so important because you can let NPCs repair stuff for you but crafting is one of the most important talents in the game imo...
