The software keyboards change based on what you're doing. Dialpad for phone, texting necessities for texting, web buttons for browsing, etc. This is what a physical keyboard can't do.
I think your collective heads would explode if you ever saw someone entering Japanese using a 10 digit numeric keypad.That is a talent...--The talented hawk speaks French.
Entry in kana followed by intellitype-style conversion to kanji. It can be pretty efficient, I'm sure.