We put it up for a few reasons

1. The CW cash shop pages are already hard to navigate. If people start submitting a lot more CWs, it'll be impossible. This is mostly our fault, but we just can't support thousands of items on a page at one time.
2. We want these items to retain value and have an imperative for people to buy them ASAP instead of waiting and then missing out.

When you put your item in the CW cash shop you take away a lot of your own ownership of the item for the ease of having all of it taken care of for you. This is one of those things. :)