You're underestimating the number of people that work with design and typography. ;)
Perhaps, but don't forget the number of people who do charts ;) - all technical workers - many students of various fields - many office workers (I use Inkscape all the time when doing reports) - people who do website button designs - comic artists (not charts, but still auto flow-in-shape)
If I were making a few big letter designs, I'd probably convert to path, select the letter and do transformations manually rather than enter numerical values (that or do manual kerning).
Of course, most of those people don't use Inkscape to do charts Now (not with some trouble at least) because of the following: - markers don't take the colour of line yet (isn't that one of the most highly rated Inkscape bugs?) - no dedicated chart tools (you have to do align manually)
But Inkscape could potentially become a major tool for creating charts.