I have tried to use Wine exclusively to play Windows games in the past but there would always be a game that I wanted to play that would force me to create a Windows partition on my system. Even with awesome resources and tools like WineHQ and PlayOnLinux, getting Windows games to run on Wine can be a pain. Also, the difference in performance can be substantial enough that I consider a game unplayable and I end up just installing the game on Windows.
I can partially agree with the argument that Wine discourages developers from creating Linux ports of games that might work on Wine. I remember people making posts about trying to play games like Unreal Tournament 2004 and Doom 3 using Wine despite the fact that both games had really awesome Linux versions. WineHQ will usually point out if a game has a native Linux port but there are probably plenty of people that will not attempt to find out if a port exists and they will just try to play the Windows version.
Although I use Wine on a regular basis for playing some games and running some Windows-exclusive applications, I would much rather buy and play games that have native Linux versions.