When you dissolve instant coffee directly into hot water, the amylum contained in the granules hardens, creating a powdery taste and consistency. By mixing the granules with cold water first, they dissolve more gently once introduced to hot water.
I found this technique makes for a richer and more flavourful coffee experience. Allegedly also because aromatics evaporate slower.
In my corner of the world, most CPs are also PTs. Or rather the other way around: they use chiropractic as one of many therapeutic means in their portfolio. I have to say, I very much appreciate this approach, as it relives the initial pain/discomfort but also addresses the underlying problem.