You can also see crafting system as a two times reward : first you get the schematics then the components. This way, you can deliver rewards that means a real gap (final object is powerful), yet it doesn't unbalance the game too much (since you need the time to get the components).
Adding weight or countless numbers of components is depending on design choices and sometimes, it may becme a bit tedious, that's sure.
In Kotor2, it as well done : not tedious and rewarding for developping some skills. In the other cases, it may quickly become tedious. In FNV, I did not at all bother crafting ammunitions. In The Witcher 2, I've used a no weight mod to avoid the tedious part of it.