Big splashy new origin stories are geared to the collector mentality. Previously (pre-80s) reboots were pretty "soft". They might ad a few new elelments each time the origin was featured in a story and those elements would become part of the origin. Or they might do a special origin issue every few years. Only a few readers cared if the origin seen in 1959 didn't quite match the one seen in 1949.
