Yeah, no need for WWI in the Boutique. Plenty of ways to farm it. To buy WWI in WC rather than farm it requires patience, lol.
Soloing WS= 6 WWI per run; 12 WWI in 2x.
If you don't like that, just do the weekendly Ares event...80 times
Only would take you 1 1/2 years to farm 80 WWI that way
But doing WS a couple to just a few times plus the Ares event, which btw can be multi-cliented, will already give you 20 or so WWI. Doing this much work, in all, would only be a couple of hours spent on hardcore farming.
If the item was added to the Boutique, it should be made quite expensive or WS Belt would be way to easy to acquire. As it is, the additional mats can be farmed through TT, which is a joke. A dozen or so TT runs will get you hundreds of EC from the chests + the rest of the mats for the WS belt.
All in all, I can see where you are coming from but...I'd rather it stayed the way it is.