When Bill Boston began building bikes bikes for short statured riders back in the 1970s, he developed the small front wheel (to size the bike to the rider without unusual, strange handling geometry) and standard size rear wheel (because he was working with five speed freewheels with 14T small cogs) design.

With the availability of hybrid hubs and cogs as small as 9T, it's no longer necessary to use a standard size (27" or 700C) rear wheel to get acceptable high gear ratios, and good handling bikes without toe overlap can be built for short statured riders with two equal sized, smaller diameter wheels. In fact, the 'small front wheel, large rear wheel' has been an anachronistic design since the early 1980s. Some manufactures continued to build bikes this way for decades, though, as sort of a 'marketing signature'.