You don't need a laptop to use the iPad. The minimum you need is basically one of those female USB > AC adapters. The Dock serves the purpose, but you can easily find some 3rd party usb adapter to provide power.
I'd say they'd need to release a Ethernet-to-dock adapter.. I bought a Netbook for the sole reason of having a computer when travelling although most hotels have wifi, most of them aren't free. Ethernet, on the other hand, is available in 99% of the hotels i've been to.
Agreed, I don't know why people keep missing this.
Alongside the SD adaptor there is a USB port add on too so that cameras can be hooked up directly to the iPad to transfer photos. As we know cameras appear on the OS X desktop as an external storage device. So it stands to reason that, assuming the SDK allows it, people could develop the ability to attach USB hard drives etc.
I don't think that the likes of FCP would be any good on such a device. But I can see iMovie being ported to it, especially given that most stills cameras record pretty good video these days.