Yes.... carrying around a full-size bluetooth keyboard will make an iPhone more palatable. Totally.
Switching language layouts? I've never done it on any device I own. Not a selling point whatsoever. /shrug. Maybe you need it. I don't. /shrug
Back in the Palm dayze, I had one of those unfolding IR keyboards for my Lifedrive. It kinda worked, and wasn't too big, but wasn't a great solution because now yer stuck carrying around 2 devices. A slideout keyboard is *WAY* better for entering contact info or search terms than dragging another piece of hardware around.