Since it was asked to move this into a new topic from the wishlist thread, and I had a few things I wanted to respond to..
I don't think many people would say Wine/Cedega/CrossOver are great solutions. If anything, it's more of a last-ditch effort, which just goes to show how much Linux users really want to try playing these games. It may not be a very good solution for actually playing, but it's rather telling about the potential user base for publishers.
Because it's a poor substitute. A native version would (read: should) be of better quality than the Windows version run through Wine/etc. A better quality product brings in more users, and makes for happier customers. Happy customers are repeat customers..
Now, having said this, for all the people claiming it's 'great', it's not all a bed of roses by any stretch of the imagination- most of the space is bronze or silver rated (using the WINE rating system ratings...) at best, even WITH Cedega and Crossover Games.
So, if people are willing to spend $20 on a poor substitute, why bother making a native title?