Google Wave is a really ambitious HTML5 app that would be virtually impossible to get running correctly in IE. Rather than telling Explorer users to go download and install another browser, which sounds like a huge pain, they tell people to just click here and get a plugin. That plugin, of course, is Google Chrome’s entire rendering engine. These people are my heroes.
Want to use Wave in Explorer? No problem!
This post is over ten years old. Chances are, I've learned enough to have advanced my thinking about some of this stuff.