It would be if you are doing corporate ads and such, but I'm a professor with slides to provide outline for students as I lecture. I have extensive notes that are in the Presenter Notes. Your little trick just doesn't do it. The whole idea is to be able to be liberated from a podium. Also, I have friends who are ministers who use the iPad to advance slides and also have their sermon notes visible only to them. There are a lost of uses that your "simplest solution" is not a solution.
Even if your solution did work for me, why should I regress to a method I used 20 years ago when we have these other methods that are supposed to work. With all the complaining we do, we should be glad we can get it to work despite the issues given what our options were without this technology.
I'm hoping that the new updates to Keynote on both MAC and iPad will solve the problem although it came out too late to test this term.
I'm also a professor and I don't use notes at all. I'm not saying this is the best solution for everyone. I'm just saying that if establishing a WiFi or BT link is a hassle, this might work easiest for some folks. It doesn't have any bells and whistles, it's not particularly elegant, but in a pinch, when you can't establish a connection, it's an easy solution that works.