Oops! Migrate2 manual page fixed.
The intention for including the arguments was to require explicitly specifying offset and default values, e.g.
configSwitch(LEN_PARAM, 1, 4, 3, "Note length", {"Whole", "Half", "Quarter", "Eighth"};
In this case, the note length is 2^{-\text{LEN}} so it’s convenient to have a different offset than 0. If the min/max values could be omitted, it might confuse code readers on the correct valid range of the parameter.