I quickly learned to avoid crafting in Skyrim, because it made the game a little boring when I stopped looking forward to finding chests. While the weapon crafting system in FO4 seems really cool, I'm loathe to repeat the same mistake.
Only way I can see it not being a problem is if the materials for some of the better components are themselves fairly difficult to find. For instance, a laser long barrel requires fiber optics, which I imagine is not exactly an abundant resource. It would be kinda neat to hunt for relatively rare materials in places where you'd expect to find them, such as MIT in the case of fiber optics.
Even then, once you've got your Plasma Boomstick of Doom assembled, what else is there to look forward to? One cool thing in Dead Space 3, which has a similar crafting system, is the circuits, which are little chips you can insert in your weapons to boost certain attributes. You find increasingly more powerful chips as you progress through the game, so even though you're still using the same weapon you crafted relatively early in the game, you can still improve it.