Apparently the only reason more people prefer a soft contact lens to a gas permeable contact lens has to due with comfort. But with the exception of initial wearing comfort, a GP lens is equal or superior to a soft lens. A gas permeable contact lens combines reliable vision correction with low cost.

Actually all modern contacts are gas permeable lenses. The original plastic contact lens was inflexible and wasn't gas permeable. And this meant that when the lens was on your cornea, it made it harder for your cornea to get the oxygen it needed. So these hard lenses couldn't be worn long without eye irritation.

Soft contact lenses were the first major improvement to the plastic lens. They were made of a material that absorbs water and becomes very soft and flexible. So although the lenses were gas permeable, their most obvious difference was how soft and comfortable they were. When the gas permeable contact lens was created, it wasn't water absorbent like the soft lens, but it could pass oxygen to your cornea and was more flexible than a hard lens. But to differentiate it from the soft lens, it was originally called a rigid gas permeable lens.

So if a soft lens and a gas permeable contact lens both allow oxygen to get to your cornea, why would you want the less flexible GP lens? The three main reasons are, the lens is easier to keep clean, it has more consistent optical performance and it's more economical.

Although a soft lens is easier to initially get use to, a gas permeable contact lens usually requires no more than a day or two and sometimes only a few hours. And the comfort of the soft lens doesn't come without a penalty. Because it absorbs water, it also soaks up other substances, which makes it harder to keep clean.

The flexibility of the soft lens extracts another cost in how it performs. Every time you blink it can change the shape of the lens slightly which can affect your vision. This is especially so if correcting for astigmatism or presbyopia. But a gas permeable contact lens holds its shape and can maintain more consistent performance. Additionally it's unaffected by any slight variations in the surface of your cornea which might cause some vision distortion.

The fact that a soft lens is soft, makes it less durable than a gas permeable contact lens. And while a GP lens costs more initially, it can last for several years, while soft contacts last no more than a year and usually less. So on a yearly basis, a GP lens is less expensive than a soft lens.