Paul is a problem solver, and if you go back to the very first guitars he made and which were the inspiration for what was to come - they were essentially Les Paul Juniors. I am sure he has stated in the past (and I am pretty sure Joe Knaggs has said the same thing) that stop tail guitars simply sound better than those with an ABR-1 or similar bridge. Being the owner of a 53 Les Paul and a couple of SG Juniors and Melody Makers I 100% agree with him on this - there is an immediacy and responsiveness to their tone and feel that isn't there with the ABR-1 / Stop Tailpiece. Added is that when Paul started making guitars, Gibson and Fender were at their lowest ebb - Norlin had zero interest in quality - their dies and machining processes had been neglected for years, the tolerance on ABR-1s was hopeless - a bunch of poorly fitting parts held together with a bit of bent wire - we could spend hours trying to chase down rattles in an ABR-1 of this period and eventually just throw it out - that's why so many Gibsons and Fenders of this era have so many parts replaced - the stock factory parts were junk.
So as a self taught engineer and problem solver, Paul looks at the ABR-1 and original stoptail and thinks; "what is the simplest, most elegant solution to this - do we need really need all these widgetty little parts when 99% of guitars have a very predictable intonation pattern, and to boot, can we make something that actually feels really nice to rest your hand on?"
What PRS came up with was one of the most elegant stop tail bridges ever made - zero rattles, NO moving parts, no "banjo-ing because there is a straight drop off where the string leaves the bridge, and it feels absolutely beautiful under the hand. Just think - if there were people at Gibson who thought the way Paul does, they could have designed this seventy years ago...... but they didn't. As much sculpture as function.
The adjustable version came along when the SC250 was revealed, and that guitar was aimed at least in part for the drop tuning dudes who frequently end up with a wound G string - prior to that demand for intonation based around a wound G on PRS guitars would have been essentially non existent.
