At this point, there is no specific reason, other than 3 volts was the maximum Vref input voltage.
However, I am glad that I actually made the right conclusion:
The Vref voltage is used as the reference for the resistance of the Sense input.
What I understand is: 1 volt as the Vref and 1 Ohm resistance for the sense = 1 amp current chopping.
After many hours of pulling my hairs out, I realize that it is as simple as:
I = V/R
OMG ! I could kick myself ! You wouldn't believe how much researching it took to get this far
Thanks for your reply Pminmo ! What tips do you have for setting the Vref voltage ? Do you have a general rule as far as this is concerned ?