I think Ruger was hedging their bets thinking not everyone would buy into their integral base idea. In the process, they created a collectable of sorts, or a better-looking rifle, depending on your taste.
My understanding was that they began providing the round-tops because a number of dealers complained that the integral base idea prevented them from selling bases with rifles, reducing their profit. I'm not sure if it's true or not, but that was conventional wisdom of the time.
