One of my favorite articles on design is a criticism of touchscreens, and how they rob us of tactile feedback in our interactions with technology (I still stubbornly use my antiquated Blackberry because I'd rather be able to feel my keyboard than have a larger screen to browse on). One of the things I love about safety razors is how they feel in the hand. Even when I was using cartridge razors that gave me a decent shave (the King of Shaves Azor wasn't bad), I never particularly looked forward to handling the razor. The quality of a shave will be largely down to the shave head and the blade, but the experience of actually using a razor is as much about the handle, hence there are enthusiasts selling aftermarket handles for popular shave heads. As well as feeling more impressive in the hand, traditional razors tend to engage more of your senses and give you much more feedback about your shave, as it happens rather than five minutes later via razor burn.
It is a "feature" of many modern cartridge razors that they allow the shave head to flex and follow the contours of the skin, ostensibly to help the blade stay close and achieve a better shave. Gillette's latest and most complicated looking razor, the "Proglide FlexBall" has a hinge intended to allow the blade to maintain maximum contact as it moves over the contours of a man's face. Great in theory, but these features essentially take control away from the user and gives it to the razor (or Gillette's product designers). I suspect the FlexBall hinge will act like a really soft suspension on a car- you will get very little feedback from it while it's in use. To me, this is a recipe for a poor shave, not a great one. A single edge razor with an inflexible head gives you a good feel for what you are doing (and with a single, thin blade often gives audible feedback as well).
As for the new Jagger models; I really like what I've seen of them so far, the shorter handled, non-rubber models appeal to me particularly, and while they don't offer significantly more feedback than the older models (for that, you'd probably need a nice hollow-ground straight razor), they have a lot of character and feel very interesting in the hand.