The penny farthing, more commonly called an ordinary bicycle, developed that huge front wheel because before the invention of the modern bicycle's chain and gears the pedals were directly connected to the front wheel at the hub axle. Therefore the only way to go faster was to make the front wheel as large as possible. The only limit was how long your legs were. Bicycles at that period in history (mid 19th century) would have been ridden only by very physically fit young men who had the financial means to purchase the expensive, individually handmade item. At the end of the 19th century the concept of interchangeable parts came along at about the same time as the invention of the safety bicycle that has the same diamond shaped frame, gears and chain, and two similar sized wheels, that is still used in modern bikes. Those developments brought the cost of a bike down to where many more folks could afford them. Women and children began to ride. Folks started using the bicycle for everyday work, recreation, and travel. That is when the bicycle really became a popular consumer item.

Wow, something I can answer!

They were very popular, as they were a massive improvement over the previous boneshaker/velocipede designs, which generally weren't comfortable, were less efficient, and heavier.

With the Ordinary (also called penny farthing) bicycles, you got a big wheel which made them more efficient, since back then the chain and sprocket hadn't been invented yet (or at least, not used with bicycles widely). So the bigger the wheel, the farther you went with one rotation of the pedals.

Ordinary bicycles were popular mostly with upper class men - women didn't really ride bicycles much until hard tired safeties (essentially modern bikes, but with hard rubber tires rather than pneumatic) came along a few decades after the ordinary.

Keep in mind, people in modern times think they look scary and hard to ride, but they were about the same height as horses, if not shorter, so the height wasn't unusual.

Source: https://web.archive.org/web/20110316053924/http://www.pedalinghistory.com/PHhistory.html

Sadly my grandfather passed away, or I'd direct him here to answer this more in depth. That's his old website as the source, he'd have loved to talk more about bicycles with anyone who would listen :P