It has been said that the only constant is change. This is very observable in our technology. A prime example is the telephone.
I was thinking about how I can still remember some of the phone numbers we had in my early childhood prior to the switch to all digits. The funny thing is, I can easily recall the early numbers that used the exchange names, but cannot recall any of the ones comprised of only digits. For example, when I was 5 years old, my telephone number was MAdison 3-9975. Later, while living in the Sharpstown area of Houston, it was GYpsy 4-2931. My paternal grandparents had ORange 7-9716, while my maternal grandparents originally had WHitney 4-2931 (later changed to SUnset 4-2931). To place a classified advertisement in the Houston Chronicle, you would call "Miss Classified" at CApitol 4-6868.
Consequently, telephone dials (remember those) had letters on them to accommodate dialing the phone numbers of mixed alpha and numeric characters. Today's keypad dials carry on the tradition, even though exchange names are no longer used in the phone number. Of course, this has proven to be a useful marketing tool for businesses, as the letters have taken on a new life in numbers such as 1-800-CAR-RENT, or 1-800-DOMINOS. With mobile telephones, the letters are used to "text" friends. (Yes, yet another example of a noun being repurposed as a verb.) This makes me wonder if young adults today have any concept of there ever having been a different reason for those letters on their phones. Or if they wonder why the punching in a number is called "dialing" the phone.
There are other examples of this phenomenon. How many people using a TiVO or other DVR, which record digitally to a computer hard disk drive, say they are "taping" a program? We still talk about "rolling down" or "rolling up" the windows in our cars, even though crank handles and manually rolling down the window has just about totally been replaced by electric windows. We even still occasionally hear someone saying "crank" the engine of a car, although cranks to start cars disappeared many decades ago, long before I was born.