It depends on what you want to do, the MF 165 is a bit big to run a finish mower to mow yu yard but to run a bushog to mow 10 or 20 acres it's be right at home.
I wouldn't say compacts are only for hobbyists, there are alot of people that make alot of money with a 25-35 horsepower 4wd compact tractor. While my needs require a tractor like what you have my neighbor has a little JD 850 4wd with a loader and I use it often to do small jobs where I can't get a bigger tractor, ie: in the yard, in tight places of the barn etc.
Just like every tool in you toolbox, each has it's own use, it's own strengths and weaknesses, and some are handy for just about anything.