If I had to choose, based on what everyone has said here so far, I'm ok with the purple labels continuing, but also would like grading companies to not offer to butcher books in order to remove restoration.
The purple label just makes it 100% obvious to the buyer that a book as been altered. It doesn't determine value or desirability of any given book, that's what the market does. And the market seems to speak pretty clearly regarding color touched books. I see OP's point, and agree with him to a large degree, but alas...
Just CGC, please for the love of pete stop destroying beautiful comics