Dining culture was so big in the 50s because of the Baby Boomer era attitudes in general. Soldiers were just returning from the Second World War and were probably looking to dine with their past separated families more often. The GI Bill (https://www.ourdocuments.gov/doc.php?flash=false&doc=76) also provided enough funds for American families to eat out a bit more extravagantly than they would've during the early 40s or the Great Depression. Simply, more families had the money to eat more and WWII veterans wished to spend more time with their families. This also lead to more babies being born in this era (leading to the so-called Baby Boom that occurred in the 50s.)

Along with money being more available to American families, many innovations were brought with the 50s. Many innovations you probably wouldn't associate with dining. The television (invented in the late 40s to little sales and popularity. "RCA initially marketed their line of TV set in New York City, with poor results" http://www.earlytelevision.org/prewar.html,) blew up in sales after WWII. This lead to companies (like C.A and Swanson) first selling the television dinner in 1953. (https://www.loc.gov/rr/scitech/mysteries/tvdinner.html) This made it so families could eat dinner and watch their favorite prime-time shows simultaneously.

Along with TV dinners, there was another huge innovation that changed the way people ate, fast food! We often associate eating lunch or dinner on the cheap today with brands like McDonald's and Burger King. These brands came to existence in the fifties. The first McDonald's opened in April 1955 (https://corporate.mcdonalds.com/corpmcd/about-us/history.html) and Burger King opened its first chain a year earlier. While these brands wouldn't truly propagate until the sixties and seventies, they were formed in the 1950s.

You can find 80s themed diners in any big city, (in New York and Los Angeles to be specific.) They aren't as rare as you may think.

Sources: The GI Bill: https://www.ourdocuments.gov/doc.php?flash=false&doc=76
Early Television: Prewar Era: http://www.earlytelevision.org/prewar.html
The History of TV Dinners: https://www.loc.gov/rr/scitech/mysteries/tvdinner.html
The History of McDonald's: https://corporate.mcdonalds.com/corpmcd/about-us/history.html