Speculating, but I suspect it probably makes the guitar feel a little slinkier because of the reduced angle between the tailpiece and the bridge. A lot of jazz guitars from the era had them. The major con of a trapeze tailpiece is that makes it much trickier to rest your palm on the bridge, or do palm muting, without knocking the guitar out of tune because the tailpiece moves. This is why, like on Reinhard's new '65 ES345, most of them get removed on rockier guitars.
Unfortunately with '52 Les Pauls, putting a stop tailpiece on also requires that the neck be removed and reset at a slightly steeper angle - which is obviously a pretty major undertaking. But with the prices of '50s Les Pauls now, this is becoming more and more common as almost no one wants there '52 with the original tailpiece (and hence they are cheaper than '54s with the wrap-around tailpiece).
From what I've read, Les Paul wanted the guitar to have a maple body with a mahogany top - which would have made Les Pauls unbearably heavy. He did suggest that they be gold and likewise had a hand in the dinner-jacket looks of the LP Custom. But most of the design decisions were made by Ted McCarty's team at Gibson. Under his leadership, nearly all the famous Gibson electrics that people covet today were designed.
