Well, partly has to do with the fact that they removed some of the things I listed that I'd want like the email client. But ultimately, it comes to this: largest version is 16GB, and my current iTunes library size is 20GB.
But assuming the next generation iPod Touch has a 32GB version, I'll be grabbing one when it comes out. It sounds like exactly what I'd want. Email support would be an added benefit, but not necessarily a requirement.