I'm not a big collector of certified coins so I may not be the best judge, but I think, generally, they're of use where:1. Authenticity is a question. Could a piece be counterfeit? Are there known cases of counterfeit MT's? How pervasive a problem is it? Perhaps in the case of plated coins, plain disks, or machine stamped, but then you'd want some accompanying documentation on provenance anyway.
2. Attribution is a question. Since there's little depth today in distinguishing, say, subtleties of die varieties, in MT's, this may not be a great concern to most collectors.
3. Grading is a question. This is a general problem with tokens. With manufacturing quality all over the board and relatively small production quantities to make comparisons, collectors are left with their own experience or comparisons to similar coins for grading. Do collector demands today result in large price differences specifically for higher and/or subtle grade changes?
Then there's also the point that having certified MT's would add more visibility/popularity to the field and perhaps give values a bump - both good and bad for collectors as seen in other cases, I think.
