If the leather in the Leon is anything like the leather VW use in the Golf, the leather in the Golf is not the best quality, and not all of it is leather - seat bolsters, seat backs, door cards and armrests are ‘pleather’ (pvc / vinyl). So you’re paying a lot for not much actual leather - only the bits that your butt and back make contact with are real leather. It can also get hot and sticky in hot weather and cold in the winter (until the heated seats warm up), and as others have said, it offers very little grip for a performance car.
If it’s still available on MY20 cars as an option, it’s not something I’d choose to have. Just my personal preference though and we all like different things.