Basically small particles means higher prints per pound and increased image quality. For example, a printer that can only print 300×300 DPI will have noticeable dots. A printer that puts 1200×1200 DPI will have much smaller dots, producing an image with effectively higher resolution; far less noticeable. Spherical particles are easy to predict how they fall on a page. Imagine rain drops; how they will land is relatively easy to predict. Drop a puzzle piece…now, there is quite a bit of confusion, especially as ink is a liquid.
Hope this helps!