Because foundries don't produce enough Greek type.
Because supporting a script, hence a language and a culture, should count for more than market share.
Because we might be able to solve some of these things with just a font.
A common issue in multi-script typography is when a graphic identity, originally designed only with Latin in mind, is later extended to cover other scripts; very often the fonts lack the necessary characters. The problem is particularly acute on the web, where texts in scripts unexpected by the web designers may need to be published. The two obvious solutions, to switch typeface to one with a larger character set, or to commission an expanded character set for the existing typeface, may not be practical.
With this problem in mind, and taking inspiration from David Berlow's parametric fonts, Irene Vlachou and Laurence Penney present their experimental system, focussed on Greek characters in relation to a Latin font. Using a specially designed Greek variable font, measurements are taken from a given Latin font and applied to the variable font. This way, a synthetic Greek font is produced that precisely matches the measurements — stem widths, cap height, x-height, and so on — of the Latin font. While not intended as a substitute for custom Greek typefaces, the results are significantly more pleasing than the typical alternatives — using system fonts such as Times or Arial. The authors propose that the system could work well on the web, where the principle of fallback fonts is well established.