Honestly, I didn't mind the absense of weapon crafting. We already need the materials we find in the wastleland for mods, power armor and/or settlements; I doubt there'd be any to spare to build weapons themselves. Besides, I think the only weapons being built post war are melee, pipe and Institute weaponry
Pipe weapons are somewhat weak (unless you heavily invest in Gun Nut), I must agree. Far Harbor is supposed to introduce more high-level gear, which is one of several things to look forward to.
It seems that Automatron is the Dawnguard of FO4, Wastleland Workshop being equivalent to Hearthfire, and Far Harbor being similar to Dragonborn in that it introduces a new landmass. So given that this is only some of the DLC (with more of them, Survival mode and Creation Kit to come) I'd say there's plenty of incentive to hang around FO4.
I always wanted to build my own robot!!!!