Originally Posted by
kcru
Because at level 14 Paralysing weapons may be awesome. At level 18 they may be pointless. Sure, You can basically junk the investment you made earlier, but it's just adding more cost.
Other reasons... maybe I have a striding ring that I made, and later I find striding on boots that I prefer. Replacing striding on the ring with something else as conditions change is preferable to having a ring that's only good for stripping down and wasting resources again.
I certainly would never consider swapping individual effects on an hourly or even daily basis. Too costly by far. In the big picture things can change. This would be one advantage of crafting over immutable greensteel... once Fortitude is on a set of bracers, you're probably never going to aquire a heavy fortitude set of armor, etc. The investment is just too high.