The main reason is taste.
Not everyone agrees organic/biodynamic/natural wines taste better (although we like to think so…!), but pretty much everyone agrees they taste different. Grapes from a conventionally run vineyard where weeds are burnt off with herbicides and mite pests are controlled with synthetic pesticides simply cannot taste them same as grapes from vineyards in which weeds were allowed to grow naturally and mites were discouraged with stinging nettle or chamomile teas. Plenty of organic growers even drink the teas they spray on the vines, because they are healthful, tasty and safe.
The era of cheap wine is coming to an end for two reasons. Fossil fuels are becoming more expensive and being heavy and fragile this makes it more expensive to get wine bottles into our shops. Second, until now, wine-growers didn’t have to pay for any mess they left behind in terms of potentially toxic spray residues (in wildlife or rivers). This is changing.
To survive we need carbohydrates, vitamins and protein – but not wine. Wine is a luxury. The best argument for eliminating toxic residues in wine is not to scare people but to reassure them that
a) organic/biodynamic/natural wines taste different and if you try’em you might like’em, and
b) thousands of wine-growers all over the world are growing grapes organically and biodynamically and getting rave reviews both from critics and normal wine drinkers.
If organics/biodynamics didn’t work, why are more wine-growers than ever before shutting the door to the place they store the synthetic sprays, and throwing away the key? Some are doing it because they worry about their own safety, or that of their workers, neighbours and local watercourses and communities, others simply because they want to “save the planet”.
But most are doing it because they say they “just get better grapes.”
That’s something we should all drink to.