There are lots of things a 4xxx series will do that a 2xxx, 3xxx won't. You want to talk about lift capacity in the loader just for a start. You can get a lot more power. By going by your theory eventually we'll end up at the John Deere 9560R that is 550HP. The pyramids of Egypt were built with no machinery at all, so do any of us NEED a tractor at all. No. We can do everything with our hands going back to the caveman days. The reason they have all the series is so everyone can spend what they want for their uses. A 4xxx will run a lot more 3PH accessories because of the extra PTO HP that the 3xxx can't. Also will run bigger items. But then that goes back to the question of should we be outside with scissors cutting 10 acres of lawn or do we want a nice flail mower for the back of our 4520 with a cab and air conditioning. Point being all are "wasteful" in your terms. We can do everything without these beautiful machines, just more time-consuming. And for you theory of acres, what if I owned 20 acres of california red woods that I wanted to clear with my 3xxx. You think a 4xxx will do that your crazy. Were talking millions in super heavy duty logging equipment for my 20 acres. The thousands in-between each hundred increment (3320-3520) is a big difference and if you can do what you need with a 3320 why spend 2000 more? Anything over a 3x20 is definitely not wasteful. My father-in-law has a 2001 JD 5410 on his 20 acre horse farm for the one reason that he has large square bales brought in and he couldn't lift them with the 3x20's period and the 3x20's don't offer self leveling and wouldn't lift them to the height he needed in his barn. For that one reason he had to get a much bigger tractor. He stacks them 5-6 bales high and can lift 3 bales at a time. a 3x20 would struggle with one as they weigh close to 2000#. Point being that they sell all the series for a reason and that people need larger tractors for different uses and they are not a "waste"
I was speaking from a general sense, not picking at details. Of course one property of 20 acres could be completely different from another. I understand where your coming from.
This person is trying to decide between a 1026R and a 2x20 series...there is no need to even bring 3x20 or 4x20 into this equation, they are a complete waste for his needs.
I disagree with you on one point, we as a society, do not need so many choices, it's plain stupid and wasteful of resources and time. A good example is the difference between a 4520, and a 4720. You know what you get for $2,000 more? 6 HP! That is it. You will not convince me that you can feel the difference between 60 HP, and 66HP. There is no need to have so many choices. They should offer the highest HP model at the lowest price tag (example: 4720 for the 4120 price tag) They would still make money by far. These tractors are hugely overpriced, and the $2,000 jump up to the next model is probably 80% profit.
It's like the SE seat people buy for X7xx series. That seat is what $500, for a SEAT! It likely costs about $30 to produce.
As much as one needs to remember what they need to do with a tractor when they are shopping, you need to remember what you don't need to do with that tractor. Always ask yourself, once all of my bigger projects are done, will I need a machine of this size? Right now, I could use a 3x20 series to tackle my big projects. It would certainly do better than a 2x20 series for the big stuff. However, once my few big projects are done, that 3x20 would become useless. Why? 60% of the time, I will be mowing, and 100% of my property can fit a 2x20 series, but not a 3x20 series. Not necessarily by dimensions alone, but weight as well.
I don't mean to say that a 3x20 or 4x20 is useless overall, of course not. If you do not need to move bales, or push/haul large amounts of material around, or do heavy ground engagement work, it does not make sense to go big. Get the most amount of tractor you feel you need right now, and the most tractor you know you can use for sure after the big projects are complete.
heck, the money I am going to save by going with the 2x20 series over the 3x20 series, as well as smaller implements, will take me and the misses on a vacation!