The Skylane is about as close to a flying pickup truck as one can get in a four-place single, and the main concern isn't so much engine size/power or fuel tank size (to feed a hungry engine), as it is Cessna shooting for the right "combination" of power, load, and fuel burn to make the venerable old airframe look good compared to the competition of the day, as far as I can tell.
Skylanes can always do one thing at a time a little better than average, but never two at the same time. True airspeed is usually 130-135. Not zippy but not a slouch. Fuel flow is usually 13 GPH down low to 11.5 GPH up high. Not great, but not that bad. Useful load is good, but if you have the extended fuel tanks you'll eat it up quick. No Utility Category, but other than tending to be nose-heavy CG-wise, it's hard to load it outside the envelope. Climb is great, lightly loaded but becomes anemic at altitude with a heavy load... Etc.
The only problem common to all Skylanes is that if you land them on the nose wheel you're going to do major firewall damage, and it won't be cheap to fix.
I mention this here because engine weight compounds this problem when someone transitions from a Skyhawk and has to learn that the trim wheel is probably going to be all the way nose-up for landing it properly and you're still going to have to haul back on the yoke.
If you didn't trim, you'll feel like your arms are getting a nice upper body workout. All that iron hanging out there and a tendency to be at forward CG limits with full fuel and two big folks up front, add up to making a heavy nose. Many Skylane owners leave a toolbox in the baggage area to get the CG back a bit.
The big fat beautiful, but heavy, Continntal O-470 is typically 1500 hour TBO (some O-470U models are 2000) and they do need care to make it that far without a cylinder needing topped. The IO-540 was probably chosen for similar weight and to get back to the more common industry "standard" 2000 hour TBO, by Marketing more than Engineering. The IO-540 derated has a 2000 hour TBO and probably makes it most of the time.
Later airframes of the 70s were either certified for 3100 lb takeoff weight or many early airframes can get it today via a cheap paper STC, up from the book number of 2950. The airframe is hellaciously strong. 2950 is still the landing weight though, so you'll be circlinYg a while or throwing someone/something overboard if you have to return "right now".
Aftermarket engines for the airframe abound, all the way up to the IO-550 from Texas Skyways, and I assume the Soloy turbine conversion is also still available but haven't checked. That ones a ways outta my league. So it's definitely not a "structural" thing.
And of course the turbocharged versions ytypically put out some more ponies at the cost of fuel burn...
The folks at P.Ponk have also done some nice work on prop sizes and number of blades with actual static "pull tests" to see how hard the aircraft pulls on the ground with different props on the pointy end.
(They also make a nice engine upgrade.) Again an argument that it's not a structural limit. Changing the prop size can significantly change the static pull by a couple hundred pounds at a dead stop.
So... while I'd normally agree that engines are sometimes derated to deal with structural limits of the airframe, the sheer number of higher horsepowoer approved STCs for the Skylane model line, kinda makes me think that's not the limiting factor Cessna was working with. Just taking all things into account as a pragmatist and not an aircraft engineer.
They probably just wanted to sell more IO-540s after the restart, from their sister company under the Textron umbrella, and chose a similar horsepower and weight Lycoming to match the past Continental O-470 for consistency. They could have gone much bigger in that airframe. But, keeping fuel and other numbers similar probably makes the airplane "safer" for those upgrading from the O-470 to the newer birds. And remember after the liability lawsuit for the seat-track stupidity, the place was (is?) crawling with lawyers. There's what, 15 fuel sumps in a restart 182? 16? I forget. Enough to be completely ridiculous, I do know that!
Toss in the turbo of the T182T and fuel flow bets are off the table though, as well as watch out if jumping into the R182 with the retract... And the TR182... that's a completely different engine, selected to lug around the additional weight of the gear mechanism and also try to keep up with the other retracts of the day...
Pretty sure the choice of horsepower numbers on the Lycoming powered birds was just to match whatever targets Marketing wanted.