Sour is the new black. From kombucha to sourbread, folks that used to have sweet coke and processed white grain bread are saying hallelujah, I don't have a stomach ache these days. It's something traditional cultures have known for years, the sour taste helps digestion.
Pickles, according to Ayurveda, excite the taste buds thereby producing more digestive enzymes in the mouth (which is why chewing your food will really help break down starches). The sour taste is comprised of fire and earth so those suffering Pitta problems such as heartburn or diarrhea, or skin inflammation problems should be careful. There is little awareness, especially with sourdough, that it can increase your Pitta dosha. Amla, or gooseberries, which is part of the famous Ayurvedic formula called Triphala, is an exception and can can calm the Pitta dosha down.
In an Indian dish, there is always a little pickle on the side to help with digestion, but it's just a little. When I was living in Portland and Kombucha became a popular "health" drink, they were serving it on tap at some bars. I think Kombucha is excellent for digestion but not a pints worth.
It is important to understand the difference of the tastes and how they can benefit us and within that, the dosage that's appropriate for each person. If you are predominantly Pitta and have a raging appetite, the sour taste may not be needed. You can also tell if you have too much because you may suffer from a "sour" or critical viewpoint on life as we believe the tastes also affect the mind. On the flip side, if you can't make a decision and feel dull in the mind, some sour taste may help you become more discerning. If we eat foods that are quite dense you can imagine what happens in the mind state.
On a bigger picture scale I think of the idea of sour being a little ignition in moving forward, whether it's the processing of foods that are cold and need a little kick, or in avoiding your whole being from being stuck in a slump without knowing how to move forward out of fear.