I have better things to do than invest time in trying Linux again. Gnome may have features that Leopard doesn't have, but my subjective probability that Ubuntu just-works like my Mac does is very low, and I'm a geeky user.

This isn't about commercials. Millions were spent in server-space commercials and Linux still came out winner because it was a cheap good-enough solution. Large companies have given desktop Linux many opportunities to catch on because it's economically more profitable. The crummy QA of desktop distributions (server distributions also have crummy QA, it's just that the geeks who run them are able to surf through it) made desktop Linux fail.