Re: Missed opportunity.
All of the problems with text mode limitations, and poor availability of colours were down to the choice of the Motorola reference design chipset. The VDG chip was perfectly capable, but limited in terms of text mode display and graphics mode colour schemes.
No amount of ROM tweaks could really fix that, although it was possible to achieve a 52 x 21 text display with lowercase by hooking new hi-res graphics mode based printing.
The add on board (from Premier Microsystems, I seem to remember) supplied an entirely new graphics generator chip. If Dragon Data had done that initially they might have had a better machine, but with far less game software from the CoCo available from the word go.
A tricky one.
Short of the BBC though, the Dragon was certainly the most 'serious' UK home computer of the era. Powerful processor, powerful basic, serious software options (OS-9, with C, Basic 09, PASCAL).