Ingineer: "It's too bad the J1772 pins were designed so thinly. They are about the same cross-section as a #12 AWG wire (3.6mm), which nobody would not consider sending 70 Amps though, let alone 30, but someone decided it was ok.".
I agree with your J1772 pin diameter, but not about your comparing that pin's diameter to that of a 12AWG conductor and therefore your conclusions about J1772 current carrying capacity.
Perhaps you misread a table, as according to NEC 2008/Table 8 (Conductor Properties) 12AWG (single strand) has a diameter of 2.05 mm, 10AWG (single strand) has a diameter of 2.588 mm, 8AWG (single strand) has a diameter of 3.264 mm. Using Wikipedia 7AWG (single strand) has a diameter of 3.665 mm and 6AWG (single strand) has a diameter of 4.115 mm.
I am not an expert on the current carrying capabilities of copper wire, but as you know the maximum current allowed for a given size wire is affected greatly by the thermal capacity of that wire's insulation. For example according to NEC 2008/Table 310.15 the 8AWG copper wire allowed ampacity for 140 degrees F insulation is 40, for 167 degrees F insulation is 50, and for 194 degrees F is 55. The corresponding numbers for 6AWG is 55, 65, and 75. Ampacities for 7AWG copper wire is not given, but since 7AWG's diameter is about half way between 6AWG and 8AWG, it is reasonable to estimate its corresponding ampacity numbers as 47, 57, and 65. There are other factors that can reduce the maximum current that can be handled safely, but 65a seems to me a ballpark figure for those pins.
It is important to note the J1772 inlet power pins are NOT insulated like conventional wires -- but they lead eventually to conductors that are and may be 6AWG or larger (anybody know J1772 inlet wire gauge for Tesla Model S?). So heat dispersal from those pins lead to those conductors and so the heat rating of that insulation must be taken into account. I don't know about the possibility of heat sinks between the power pins and the insulated conductors, but it doesn't seem to be a stretch to think that 3.6mm power pins might not be a problem at higher amps just looking at its current carrying capacity.
Now the reliability of the J1772 connection may be another matter entirely!