Why did everyone with impacted wisdom teeth used to get them pulled?

PAIN. People with true pain will often go to great lengths to remove the source. Having teeth close together without pain would not be considered clinically important and thus not drive one to have the teeth pulled. Timed removal of select, paired lower and upper teeth during the pre-teen or teen years may prevent the wisdom teeth from becoming impacted & decrease the need later.
To avoid pain. Most people's mouths are not big enough to allow the wisdom teeth to erupt (come into the mouth). If they do erupt, it is often a partial eruption. The wisdom teeth are too far back for most people to clean properly, and the portion that remains under the gums often packs food and becomes decayed. Partial eruption and/or impaction and decay can be very painful. The best option is extraction.