Sometimes I still play first series, however I never put any skill points into armor crafting or weapon crafting especially when there are so many powerful items in Underdark campaign I wonder if it really worth doing these items? Can you make fast gold out of it , can you make magical armor or weapon?
Yes, you can make magical stuff. Whether it's useful will depend on your character, though somebody in your party will probably benefit tremendously from custom weapons. I found Keen to be a particularly valuable attribute, since most of my builds relied on crits (My dual-wielding kukri weapon master/thief dealt critical hits 55% of the time, gibbing most enemies on the first sneak attack).
In later NWN2 expansions you can craft some especially potent items, especially from unique materials (Belt of +8 strength, for example). You could do some pretty crazy stuff in the original NWN2 campaigns too, like the mithril full plate wearable by a bard (with the skill that lets bards wear medium armor, of course).