Most people use their daily vehicle to drive to work, pick up groceries, travel, ect. On-road use is clearly the main reason we have our primary vehicles, although some of us plan on using our vehicles for other tasks, whether it be off-roading, racing, or joining a car club and going to car shows. People that are devoted to motor vehicles look for more than if the next prospect can bring them where they need to go on a daily basis.
When I have a chance to work with a new flux, the same thing happens. I obviously need to know if a flux will work for its intended purpose, for instance soldering SAC 305 spheres to Ni/Au or removing oxides from Sn/Pb bumps on a wafer. This is good for starters, but I like fluxes that can 'go off-roading'. Lucky for us, many of the newly developed fluxes can be used for purposes far removed from their original intent. It's nice to work with products that are not too sensitive to process variability or design.