The move by Etsy would, in theory, make it easier for people to leave themselves favorable comments and boost their numbers or to complain about everything they buy. (Anonymous complainers can't have their complaints easily ignored.)
The implications for any chain with a major Web—or mobile—presence are intense; preserving the integrity of comment and customer rating systems is essential to that feature influencing sales. Etsy took several good steps to minimize harm, such as making sure that sellers know the real identities of complainers and, of course, that site admin stills know all. Even though these moves may prevent blatant fraud—when, for example, a rival posts untrue criticisms—they can't prevent two of the most common issues.
The first is sellers themselves posting self-favorable comments (they'll certainly not rat on themselves). The second issue is dealing with problems that don't rise to the level of fraud, which means the site can do little to fix things. This issue includes buyers who comment negatively on everything they buy.
The value of anonymity is simply allowing consumers to comment on items they may not want the world to know they purchased.
Historically, retailers have relied on a large volume of comments, hoping that if 800 people comment, the legitimate posts will undo the damage from bogus folk. That requires a faith in mankind that is harder to believe in these days.
All in all, the change is probably a good one. But it's more an absence of bad. Fraudsters—or simply discontented people—are almost certainly going to use bogus names and E-mail addresses anyway, so the anonymity is most likely protecting (mostly) legitimate consumers. Although this approach won't make the fraud problem any better, it's likely to not make it any worse, either. And if it legitimately protects the privacy of some consumers—making them more comfortable posting honest comments—that's a net win for E-tail.