IMO, the recessed cylinders serve no purpose other than to make the gap between the frame and cylinder smaller. Looks good, speaks to quality and craftsmanship but practically speaking you can argue that they're a potential detriment to function. It's harder to clean down in those recesses, so debris could prevent a cartridge from fully loading. The pro-recesses guys will say, just keep your gun clean, and they're right but we're talking theory here.
Also, if you can't see the cartridge rims, you have to open the cylinder to check. That doesn't bother me, but without the recesses you can see with a glance from the side if the revolver is loaded or not.