From what I've read, it was designed for tactical teams that have to shoot around a shield of some kind. With a revolver you don't need to worry about the slide hitting the shield and knocking the gun out of your hand when it cycles, and it just wouldn't be tactical without places to mount a bunch of shit to it.
It's actually a VERY nice gun in it's own right. Ball detent lockup, polygonal rifling, Chamfered charge holes. That being said...
Lock lock lock lock! The Godwin of S&W revo threads.
Also doesn't help that the triggers on newer guns are absolutely positively horrific in comparison to every older gun I have tried. I would never sell my 627 even though I don't shoot it right now.