Ersatz Eye, why attune?

The Ersatz Eye from Xanathar’s Guide to Everything seems to me as ‘almost’ an entirely cosmetic item.

It would seem to that the loss of an eye is a storytelling option and the choice to remedy it by using the Eye (rather than some sort of healing) is also more of a "rule of cool" thing rather than something that gives a mechanical benefit.

Is there some rule or game mechanic that I’m overlooking that requires that this item need attunement?