I love them and agree that the size issue affects their popularity. The 1921 Ruth is one of my favorite cards. The other reason, especially for set collectors is that for most years are not dated. Cards issued 1947-66 are grouped into a single set, at least according to my old vintage catalog. An extreme eample is the Ted Williams (9 showing), a great card. It's listed in the catalog as a 39-46 Salutation Exhibit, but I've heard it was produced well into the 1960s.
This site does give information on dating Exhibit cards
https://keymancollectibles.com/exhibitdatechart.htm