I'm not in full disagreement, but allow me to play the devil's advocate for a minute:
- I'm sure the old truck molds were well worn out after tens of thousands of uses over the years, so no surprise that Lionel opted for a retooling at least. The new trucks are much crisper in their side frame details, and include the nice molded in lettering. They visually look more like Atlas trucks now, which is not a bad thing at all.
- As an engineer I can say, if a new design is simpler, cheaper, and can accomplish the same goals, there is no reason not to go with it. The old design was reliable, but rather complex for what it was.
- There are no small number of individuals who model two-rail or even three-rail and prefer scale couplers. I can't for a minute criticize Lionel for catering to this segment especially with the scale offerings.
- Considering the history of zinc pest amongst various die-cast parts, especially trucks, I would never have a problem with using plastic components, as long as they are robust. Most modelers in HO and N use simple plastic designs for their truck frames. Plastic can also decrease noise slightly, by transmitting fewer vibrations into the body of the car.
That said, I do prefer the hinged coupler design for tight corners, and the functioning springs. Although, the weight of these cars mean even the "functional" springs don't actually function much unless you're pressing down on the car by hand. I also find the new design frustratingly harder to open the knuckle (some very light weight oil helps), although on the flip side I'm finding they randomly pop open much less often compared to some I have of the old design.
The thumb tack is, however, unacceptable in my book on a scale model and I am pleased that they are rectifying that with the tab design, though it's not the most robust.
So would I personally have preferred that they stick with the old design? Perhaps, but I don't find the new design the end of the world as long as the thumb tacks are gone.