In reply to Deadeye:
Again, this has to do with optimisation. It's a great testament to Ray Jardine who was a nasa engineer that what he produced was more or less optimised. But lets deal with your examples:
Helmets - a complete lack of knowledge about what was required of a helmet lead them to be over engineered. Added to this they were glass fibre - essentially what has happened with helmets is they've removed the glass, made the shell out of what remains, the PE and then made that as light as possible whilst retaining the impact resistance as set by UIAA standards. I.e. there is no excess material
Old Alpine rucksacks used heavy duty cordura, heavy frames, thick padding etc. and they lasted until they fell apart at the seams through overuse. These days the fabircs are paper thin don't last particularly long, the foams used are much more cut away than they used to be.
Ropes - Again size - this has absolutely nothing to do with materials as the material is within a gnats chuff the same stuff as it has been for decades. Sure manufacturing methids have improved by PA6 is still PA6 and weighs the same. But ropes have gotten thinner and thinner, partly because of the better manufacturing methods, and partly because a lower margin of safety has been deemed acceptable.
Already explained the carabiners.
6mm slings are far less abrasion resistant than 1" nylon. There is a huge margin of safety with a 1" tape which again has been deemed unnecessary. But you will find that if you test residual strength of a 6mm tape after a few years it will be massively reduced - maybe by up tp 50%! Not so with a nylon tape.
B2 boots - well they've changed steel shanks for plastic and leather for plastic so purely lighter materials on that one. You'll find an all leather boot is still a little lighter than they used to be but no THAT much.
Wooly jumpers... can't really say much to that one...
Ice axe penetration has ben massively improved through design and thus it allows them to be lighter. But there again I remember when MT Vertiges came out they were 550g which would be about the same time as the Barracuda and chacal. Admittedly it was like punching ice for the day, but there aren't many axes which are much lighter than that these days - maybe the Grivel North machines and axes of their ilk. There I'd say the shift change has come from improved performance.
Rockboots - well who the hell needed a boot anyway?
Back to the cams though - I'd have to look up precise numbers but the gist is that on smaller cams the stem on a flexible unit consitutes something like 70% of the total weight of the unit. So taking a WC Helium as an example, I can tell you that the sling weighs about 11g, the copper ferrule that joins the two pieces of steel together weighs 12g, the stainless termnation at the other end is 12g, the 7x7 stainless cable for the main stem is about 25 g, the thumbloop cable about 15. All that adds up. And to meet strength requirements you cant go down in size. The cables are rated at I think it's 14-15kN. You might be able to exchange materials but what to? Titanium is hugely expensive so that would get passed on, you might drop a third of the cable weight and termination weight, but then you combine Ti and Stainless or worse alu you get Galvanic corrosion. The lobes them self are more or less optimised already. Swap to magnesium and you take a huge hit on tensile strength so you need to put more material into it. And it's massively expensive. So the only way to change your lot whilst retaining a flexible stem is to get radical and start removing steel and replacing them for chemically inert, high strength composite materials. But even then you'd need to be careful. Carbon for example is one of the most galvanically corrosive materials about so you need to design the material interfaces very carefully. I could go on but my point is that Cams have actually been designed pretty optimally from the start!