The main benefit to setting up a Wi-Fi network with WPS is that one can pick a secure password and still set up devices very easily. That is, it's possible to pick a secure default password or generate a cryptographically secure one and not worry about typing in a long password. It also means that devices can ship with encryption enabled by default after setup with minimal inconvenience.
The benefits of this cannot be understated. I set up a 20-character random password with 128 bits of entropy and I found my friends routinely had trouble typing it in. I am not the only person to have this problem; my colleague reports exactly the same situation. WPS provides sane, easy, secure defaults, which means that for most people, it dramatically improves the state of Wi-Fi security.
There are certainly some attacks on the protocol, and for people who don't want to use it, they don't have to, but overall, by improving default security, it's a big win.