Moonlight - a very perceptive group of students you have, there! Yes, I believe that as gloves have evolved, they have gotten lighter. That is by design, of course!
Early gloves used thicker, heavier padding in the palm and finger areas, because there was little or no "pocket" in which to catch a ball. As the size of the gloves evolved, so did the pockets. Now, a player rarely catches a ball in the palm of his hand, so there is less padding there. With advancing technologies, glove padding has evolved, so that lighter, thinner materials can do a better job of dispersing the impact of the ball than the old, heavy wool felt.
I also think the leather has changed. Glove leather used to be stiffer and heavier, in my opinion. Now, the leather seems thinner, lighter and more flexible. That is not necessarily a bad thing, however. New tanning and finishing processes can make a 4 oz. piece of leather as strong as a 6 oz. piece. Glove construction may do as much for the shape and form of the glove as the stiffness of the leather used to do. In other words, a modern glove does not have to be constructed of leather heavy, stiff and thick enough to support its own form in the glove.
Just my opinions ... free and worth every penny!

Yes, I still have my first glove.