It's a tradeoff. In my case, I bought a 1600 or so pound CUT, one notch up from a SCUT because I wanted to cut the grass with it. Since then I've bought a garden tractor to cut the grass, and I no longer have a pressing need for a light tractor. I do some gravel work on a 1/4 mile right of way, and I clear the snow on it in winter. Most of the snow work allows be to work on the downgrade, so it does a good job. I can do good work with a five foot box blade as long as I don't try to pull too much material up hill. Now, I'm looking for a slightly heavier, more powerful tractor, around 40 hp, for a stronger / larger loader and more PTO power to run a
chipper/shredder. I would also use the stronger loader to try to pop out some rocks from the grass that the smaller tractor can't budge. Thing is, if you are going to cut grass on a regular basis, I don't think a 4000 lb. or bigger tractor makes a lot of sense. Ok to cut a field a few times a year, but not for the lawn, at least, not here where drainage is a problem and climate change is turning us into monsoon summers.
The one thing I would suggest to people is that if you do buy a small tractor and want to go bigger, you'll likely be looking to upgrade your implements as well, which can be costly. For example, my 5 foot cheapie box blade is fine for me. But I've read that the same brand, when used on more powerful tractors in a 6 foot model, is prone to bending. If I upgrade my tractor, i'll likely be using the 5 footer and not be able to cover the wheels, which could be a problem. Not sure yet. Same with mowers, etc. I tend to be looking at heavier tractors now for the simple reason that the heavier tractors in a given horsepower tend to have stronger loaders. On the other hand, very light tractors like mine or the Kubota B Series could be perfectly fine for someone who is going to be cutting grass or a field. They would also have the power to run a pretty serious snow thrower, though you'll want chains for sure. If you're going to get into serious dirt work, then the weight obviously becomes more important.