1)Consider the hundreds and in some cases possibly even thousands of solder joints within many electronic components. Why worry about a few more external ones?
2)In a properly soldered joint there will be extensive direct contact between the conductors being mated, so the resistance of the surrounding solder shouldn't matter.
3)The resistance of a properly soldered joint is likely to be negligible compared to the resistance of the wire being soldered, due to the great disparity in length.
4)In many applications, especially line-level analog interconnects, fraction of an ohm resistances will be totally unimportant anyway. Assuming, that is, that the line-level components being connected are not susceptible to ground loop issues as a result of poor design (in which case the resistance of the ground conductor might be of some significance).
Regards,
-- Al
