That's why 45rpms were a staple in the 50's up until the mid 60's I think. When the late 60's came songs got longer and there was really no better way to do it than to go with full albums.
Catfish Jones said:
Singles were the bread and butter for those 60's bands, so when they'd throw an album together a shit load of the stuff WAS actually filler. I think the earlier singles are my favorites, but of course the full lengths hit their peak in the early/mid 70's.