Peace -

While your link touches on some things that influenced the development of the 45 RPM record, it ignores the documentation that supports that it was developed to make automatic changers for single tune records more practical - at a time when changers were clumsy, expensive, and prone to damaging the records.

The large hole made it relatively simple to build a selection, holding, and release mechanism directly into the spindle. In typical home players/changers, you just piled a bunch of records on the spindle. The mechanism dropped the bottom record, but it also had to keep the remaining records from dropping. Previous record types generally had constant thickness, or the label at the center made the thickest part of the record at the center hole, so that at the center, there was only a tiny "crack" between records.

The 45s, at least in earliest production, actually had a thinner area at the hole, so that there was a built in "gap" between records that a "blade" on the spindle could enter without damaging the hole to separate the stack from the record about to be dropped, instead of the "stop" for the next record having to force its way into a nominally zero width crack - and chew a hole in the record big enough for it to fit.

Evolution in changer mechanisms made most of the more subtle features of the original 45s mostly unnecessary, but at the time of their introduction they made it a whole lot easier to design a juke box.

John