When considering a tablet/keyboard combo vs. a Chromebook I think the Chromebook is better in these ways: * bigger screen * full-size keyboard * bigger and better trackpad * better CPU and more RAM
Tablets, even with keyboards, don't really give the user a desktop browser experience, but the latest Chromebook does. Also, if you need multi-user support, the Chromebook is much better choice than an iPad or Android tablet.
You don't need a keyboard with a tablet, but you have the option to use one if you prefer. A tablet such as the Asus transformer prime along with their keyboard dock can be purchased for less than this chromebook. The Asus transformer keyboard also adds additional battery life to the tablet wich can bring the battery life to over 14 hours. The keyboard does also have slots to add additional memory.
You say that the chromebook has more functionality? I don't see it, maybe you can elaborate on that? The chromebook is limited to what you can do in the Chrome Browser. From what I gather a tablet has more functionality, since you can also use apps offline. Also a tablet is slightly more portable and has better battery life. Also if you really need more functionality you can purchase a full blown PC laptop for around the same price.
I think the chromebook is a great Idea and being a gadget junkie I would love to own one. I just can't justify this price for what it is capable of doing. I'd even rather get Google's new Nexus 7 tablet for $200, it has a chrome browser and should be capable of everything the chromebook does and it also includes bluetooth and gps.