I think the problem that you are running into is that while the concept is simple and essentially what they have done is make it simple to upload/download files and easily share across computers with yourself and others, this is a nontrivial problem. On top of that, the implementation works seamlessly across different operating systems. The reaction you are running into is probably akin to people who love the iPod. A device which does one thing and does it well.

As you have seen others mention, by creating a solution to a nontrivial problem (and if you have ever had to deal with file synchronization you know this is not simple) it has enabled usage scenarios that were previously too difficult to accomplish or at least not worth the hassle. So I can understand people's reactions to your comments.