You're almost entirely missing the point. No-one is having any difficulty with roman numerals. Instead, he's presenting it as a demonstration of (1) a code-golfing technique where he tries to find a 'magic formula' to do the conversion in as few keystrokes as possible, and (2) optimizing code and/or algorithms to search an intractably large search space in a reasonable time period.
Re-read the first installment again...
When your only tool is a hammer, all problems look like your thumb.