I've thought that for a long time. I know a handful of people who truly need a Mac Pro, but even they aren't as hot on it as they once were). But they've always had towers, audio cards, loads of RAM, a few drives installed, etc. I've never been part of that world, doing those things (music/audio, etc.), so it's never been something I've had to think about or buy for.
I think 90% of the planet would probably do just fine with a MacBook Air. Luckily for Apple, a lot of people don't agree with that.