Try as much as I want to like the shirt, the attribution of this to Shakespeare over Tolkien just rubs me the wrong way.
I know before anyone points out, Shakespeare did say something very very similar in The Merchant of Venice "all that glisters is not gold" which in modern plays is rendered as "all that glitters is not gold". I also know that Tolkien's direct quote is "all that is gold does not glitter". So the text on the shirt is not a direct quote of either.
I guess I am frustrated because I really want to like this shirt but am hung up on a technicality and can not force myself to.