I wouldn't buy one now. But I am sure some others will.
Maybe purely for novelty or nostalgic reasons rather than practicality, I guess.
But the idea of air cooled engine system defintely is attractive, because it is one less thing to go wrong, i.e. Radiator, coolant, thermostats and water pump ... in fact quite a few, right enough for the price of sacrifice of the engine power and efficiency.
Don't be fooled by the air cooling being foolproof. Being in the back of the car, there is no natural airflow, and the cooling is controlled by a thermostat and flaps to direct the air. They do overheat, with various symptoms.
When you open the engine lid, it should be sealed, in that you should not be able to see past the engine to the ground below. Air flows in through the grilles at teh rear pillars, is then pushed by the fan down under. How much is directed across the cylinders is controlled by the thermostat.
If there are any gaps in the undertray, hot air will re-enter the engine bay to recirculate, then the engine runs too hot. An overheat does not have to be a significant rise in temp, just above the tolerance threshold will gently cook it, taking a long time to cause failure.
A popular failure is fitting the inccorect plug leads. These must seal. If they don't the air recirculates, and often a plug will pop out, bringing its thread with it. This can also cause the plug to run hot, burning a hole in the piston. The forward cylinder on the left of the car is the most susceptible to this.
A good reconditioned engine will include a new thermostat, and instructions on how to set it up.
Other symptoms.
A piston starts to 'pick up' in the bore. Small aluminium filings are created. There is no oil filter, just a gauze strainer in the sump. The filings can get seize the oil pressure relief valve. If seized open, low oil pressure results, and a big end will seize on the crank. If it seizes shut, the oil pressure is too high, causing leaks at every seal, and often the oil cooler, sitting on top of the engine will burst.
Valves have been known to seize in their guides, pistons in the bores, big ends on the crank. Result seems to be a bit random, but overheat is the cause.
As well as gaps in the undertray, the fan at the back of the engine can get dirty. It picks up dust which builds, until the fan is seriously out of balance. As this is driven directly by the shaft through the dynamo or alternator, the vibration can cause the dynamo/alternator mountings to break, or alternators to crack their casings.
Add to this, working on them is like sticking your head in the kitchen cupboard.
Not a fan.