I do get why some people dislike the sandwich thesis. From the standpoint of providing evidence that you deserve the PhD, it's fine. We judge research performance by published papers, so publish two or three good ones, print them out, and graduate.

If we're talking about the quality of the actual thesis as a separate document that has value on its own, the sandwich thesis isn't great though. No one would argue that it needs to be an entirely separate piece of work from your papers, but there's a legitimate case for requiring it to be pretty heavily edited into something resembling a book rather than a collection of articles on the same topic.