So the reason for the smoothness, perceived or otherwise, is that no force from the scalse/frame is required for alignment of the blade. The blade's alignment is determined by the bushing in the center of the blade tang. The blade rides on this primarily, rather than the washers. This is why, on a knife of this design, if you disengage the lock the blade simply falls free; you have a system where tight tolerances allow a very low-play low-friction design. If I were to see comparable low friction opening from a more traditional design, the blade play would be simply enormous.
No, technically you don't need the bushing design (threaded from both ends) to get this effect. You can use an enlarged pivot screw (size allows looser tolerances, as the larger diameters allow absolute diameter differences to be a smaller %) which is just very closely fitted in size to the blade tang hole. Other knives have done this. For a variety of production reasons I'm guessing, there is practicality to threading a bushing at both ends.
Not quite true. Smoothness is the result of a lack of change in resistance to force either opening or closing the knife. All of my "excessively tightened" knives are very smooth--they simply have much more resistance to opening than otherwise.
On a knife without a bushing/stepped pivot design, and which uses the more traditional pivot design you can still get the knife to fall freely by disengaging the lock. An Axis lock is a good example. Yes, some fiddling is required, but you can loctite it once it is dialed in and still have no blade play. I have a Spyderco Dragonfly that will swing freely if I hold the lockback open, and which still has no appreciable blade play.
Practicality-wise, it means that during assembly less orientation would be required of parts. Since the stepped pivot is reversible, it wouldn't matter which way it is put in. I'm not sure, but it is also possible that the same stepped pivot used on the Para2 is used for the new Military. It may be difficult to tell from the picture, but the screws seemed cut (rather badly, I will note) from a larger screw as the non-head ends had jagged cuts on them and both screws are of different lengths due to this. I would be very surprised if this was intentional.
If you like your knife high friction, and view it from a purely end user standpoint (meaning ignoring production practicalities), then the bushing pivot may make no sense to you. If you like your knife easier to open (which you've noticed this is too fast and light for your tastes) then it has its obvious advantages. I'm guessing it has production advantages as well.
Or let me flip the whole argument and put it all in another perspective for you:
Why are the Manix2 and Para2 (particularly the para2) so damn popular? You could argue egros, lock, steel, grind, size, etc, but the bottom line is one thing people seem to just love about them is the action. One hand flick the knife open or closed just by pulling back on the lock. Yeah okay, the military you can't do that with the lock through part of the blade's travel, but it doesn't discredit the feature. From spyderco's perspective then, perhaps adding the bushing pivot system could increase the knife's appeal.
Yeah there will always be the porshe curmudgeons, but I'm guessing this will be a popular change overall. I could be wrong.
They are popular because they offer great value, are made in the U.S.A., are offered in a variety of steels if you can catch a sprint run, and there is quite a bit of coverage of them on Youtube/other review sights. The Axis-lock offers similar action, so I'm not sure that that is a good argument. Besides, Cold Steel Triad Locks appear to be quite popular, and those have a reputation for being very stiff and hard to open.
I'll be honest. I'm in the minority on this one. This makes sense from a production standpoint, a marketing standpoint (whee! look how fast our knives flick out!), and a unification of product line standpoint. As you rightfully point out, the Military will join the Manix 2 and Para 2 as knives that have a stepped pivot. I'm not sure, but I think that the Native 5 may also have one as well.
I guess I'll just resign myself to being one of "those guys" that manage to complain about everything
I'm not trying to pick a fight or be disagreeable, I just don't see any upside on this engineering change. Call me a curmudgeon. 
