Years ago car body panels were made with hydraulic presses that could make those curvy shapes that older cars had, however, a hydraulic press is expensive and slow. A mechanical press can churn out those panels at 4x the speed and at a fraction of the cost.
Modern cars are apparently 'very curvy' but if you look closely you will see that the curves are done in plastic, not metal. The metal parts have relatively simple curves to them, when painted the same colours as the plastic bits it all looks good and far from 'boxy'.
As for tolerances - 'fit and finish' - there is more to it than the gaps in the panels. There has to be some tension in the panels for them to hold their shape. A bit of curve is important for this. Compare with vehicles that have totally flat panels, e.g. a Land Rover, where the panels are 'wrinkly' and far from smooth, even if fresh out of the factory.
There is also the matter of platform engineering. In the VW group the bolts that hold the engine in place are the same no matter what the model or the engine size. The Golf has dozens of same but different variants on the same 'platform' : Audi A3, Audi Q3, Audi TT, VW Golf, VW Jetta, VW Eos, VW Tiguan, VW Touran, VW Scirocco, SEAT León, SEAT Toledo, SEAT Altea, Škoda Octavia and so on...[1]
All the other volume manufacturers have the same platform based approach, the fundamentals of the car are worked out for the 'Golf' version and then after that the marketing folks and some kids with clay put together the 'remixes', e.g. the Audi TT for the 'hairdresser' market, the Jetta for the 'minicab driver', the SEAT Leon for the 'younger sporty buyer' and so on.
I believe a trip to the paddock at Silverstone is probably the best place to get appreciation of the Ferrari grade cars. The fit and finish on them is not what you would expect when inspected close up. Furthermore, the actual engineering is quite crude compared to the 'Golf'. But, if you are racing and need to fix the car between races then 'crude' is pretty good. If you are going to be rebuilding the engine all the time anyway then who cares that the bushings are primitive and prone to wear out after a few hundred miles? With the 'Golf' there will be rubbery bits mounting the engine, on a Ferrari it is bolted straight onto the chassis with no effort made to damp the vibrations, again not important if you are setting lap times around Silverstone.
Ferrari cars were styled by Pininfarina and the coachwork built by Scaglietti back in the 60's, Fiat subsequently bought the coachworks bit (as per Rolls Royce and Park Ward). Those panels on a Ferrari are very much 'coachworks' built, even if nowadays with carbon fibre composites etc. This is a very different way of building a car to the mechanical press + bits of plastic approach that mass produced cars use.
So yes, the shape is part of the cost. Personally I would prefer the 'Golf' to the 'Ferrari' and this comes down to childhood experiences of visiting car plants. The mass produced cars (MINI) fit together PERFECTLY every time. In the olden days, next to the MINI production line a smaller amount of panels were made for the Jaguar and other brands that used the same body shop for historical reasons. These panels for the deluxe cars had teams of people hammering them into shape as the tooling for them wasn't any good. They didn't fit perfectly!!! Sure the posh cars might have had leather seats and other fancy things but the basic shell was not good - 'lipstick on a pig' is the phrase that springs to mind.
As mentioned it is worth visiting 'the paddock at Silverstone' to look at some of these Ferrari type of cars close up. Also on the track. The Porsche 911 is a relatively tall and 'road car looking' compared to anything that it races against, e.g. the Ferraris, Mclaren things and what-not. Cars for the track are a very different breed to those designed for 'sitting in traffic'. Ferraris obviously have the race heritage and the track mechanical starting point, plus they are still 'coach built' and therefore 10x expensive (which is a minor cost if you are out racing).
[1] https://en.wikipedia.org/wiki/List_of_Volkswagen_Group_platf...