Netbooks around well before the air were also lacking optical drives, so Im not sure how it was controversial.
Apple did not invent the 'sub-notebook' form factor. There have been many notebooks without optical drives before it.
But more to the point, a netbook was optical-drive-free because you weren't expected to use it for more than just web browsing; you weren't going to need to load software onto it. The MBA was optical-drive free in spite of it being intended to be a fully-functional notebook computer. You would install software onto it over wi-fi. And you wouldn't need to rip CDs because you would buy all your music from the iTunes store. In 2008 that was still a bold idea.
Of course, one could argue they were specialist laptops which never had a large market. But maybe the same could be said of the MBA?
Apple's abandoning of the optical drive played a huge role in ensuring everyone provided a non optical disk way of getting their software or media content.