Well, technically the HX-20 wasn't text only, it could do bit-mapped graphics if I recall correctly. The 20x4 screen was dot-addressable.
Hmm, what did people do with them. There was a word processor of sorts (SkiWriter), but wow, would that be painful. I have a copy - maybe I'll try it out. You might be surprised to know that HX-20s are still used in some industrial applications. A company in Colorado still sells them new or refurbished for those quasi-embedded applications (they are darned expensive though).