Two recent experiences reaffirmed the same :
🎤 At a recent product talk, the presenter talked about how Google's flu program failed when a simple heuristic approach worked wonders
Google Flu Trends (GFT) which used big data analytics and a black-box algorithm tried for years to predict flu outbreaks without any success (was wrong for 100 out of 108 weeks) and the program was finally terminated in 2015. However a surprisingly simple recency heuristic forecasted the flu outbreaks more accurately - based on psychological theory of how people deal with rapidly changing situations.
📖 Read a book on Small Data by a renowned branding consultant who has transformed major brands like Lego, Lowes etc using ethnography and understanding the entire ecosystem the users interact with.
Big data is important for decision making, reporting and assessing the overall health of the systems - it's effective in rational domains (what is already known). Small data has outperformed big data models in predicting outcomes, such as U.S. presidential elections, or other uncertain events, such as consumer purchases, patient hospitalizations etc.
A combination of both would be a powerful toolkit to have.