Contrary to what you say, I think having Wine *is* a good idea.

Wine should not be used to run everyday applications, like browser, email, etc, but may be used to run the "occasional" apps which Linux users don't want to boot into Windows for

For example, if I have a configuration program for my external dongle-spanner 1000, which uses the serial port, I don't want to have to boot into Windows *just* to run this program once. The makers of the dongle-spanner 1000 probably have a 1-man software team, and do not have the ability to port the config program to Linux, plus also, they point out that you only actually have to run the config program once.

Therefore it *is* useful to have Wine.

The other reason is games, which there are relatively few natively written for Linux (yes, Quake, UT, etc). Games companies will either not care, or say "We'll port it to Linux provided it's easy enough", to that end they can use winelib etc, to make porting easier.