Tractor size and configuration has changed substantially over the past 30 years, even more over the past 50 years. 50hp and under tractors, at one time, were serious ag machines used by farmers for tillage duties on the many, many small farms so they were 2WD and designed primarily for pulling. Their HP to weight ratio was more skewed to weight. Loaders weren’t ubiquitous and hydraulics were sparse. All you needed was a 3 point and maybe one remote to run a cylinder on a plow or disc.
Now ag tractors are much larger, have complicated guidance and monitoring systems built in, and are almost exclusively front wheel assist or 4WD. The 75hp and under market spends a much lower percentage of their hours in tillage.
As the market has changed, lighter, smaller tractors with front wheel assist, loaders, and much more capable hydraulics have taken over the small tractor market. They’re much more “utility” than ag. For instance, my L at 47hp can be configured for anywhere from about 3,000 lb to more like 5500lb and has several tire choices for its width adjustable rear rims, all of which depends on what you plan to do with it. In physical size and weight it’s slightly smaller than our Farmall H which is only 26hp on the PTO compared to the L’s 39 PTO HP and is similar in weight. The L, however, is a much more versatile machine with a fully functional loader, third function, rear remotes, and lower center of gravity. The H was designed to pull, period. Modern tractors designed to pull, period start at MUCH higher HP. The L, and most tractors under 75hp or so, was designed to be a Swiss Army Knife of a machine; not great at anything in particular but good at a lot of stuff.
So, yeah it’s not surprising to see older tractors be physically larger than their than their modern counterparts of similar hp. Or older tractors being lower hp and less festooned with hydraulics than modern tractors of similar size/weight. It’s partly a function of technology but more a function of manufacturers reacting to changing markets for their products.