Mobile USB charging ports (as found in airports etc) are more of a gimmick than anything else. A shoddy one will easily damage your device, and if you're constantly plugging into different ones, that seems like just a matter of time. Plus, an unknown one will most likely just put out 500mA (slower charging), and USB A connectors aren't made for high insertion cycles so expect flaky connections. Plus you still have to carry the bulkiest part (the cable) so you still need kit.

I personally just carry a three way AC power splitter cube while traveling, which gives me enough ports for laptop+phone+whomever I ask to share with.