First, a word of clarification. "Less current than there otherwise would have been" doesn't mean that the current is actually "low". Remember that HV lines service multiple houses, so the current flow through them is still typically higher than what flows into a single average home.
However, the current that flows through the wire isn't what makes it dangerous to touch the wire or not*. What's important is the current that flows through you when you touch the wire. So, the question becomes, "how much current would flow through you if you touched the wire?"
All else being equal, the current that flows through you is directly proportional to the voltage across you. Double the voltage, double the current. And that's why it's dangerous to touch a high-voltage low-current wire: The high voltage will push current through you regardless of what the previous current flow was.
However, that's not the whole story. The fact is, there's no such thing as a perfectly constant voltage source. Your body would represent an additional load to whatever the source of electricity is, which would tend to pull the voltage down. High-voltage air ionizers and ozone generators are (usually) perfectly safe to touch, because their power supply circuitry has next to zero current delivering capability, so touching it cuts the voltage to a tiny fraction of what it was with no load. Electric fences (for cattle or pets) have a somewhat higher capacity, so the voltage drops enough that its not dangerous, but still enough to give you a little zing. For electrical power lines, though, the load presented by your body is incredibly tiny compared to what they normally supply, so the voltage drop is undetectably minuscule, and you get the full voltage across your body with all the current that that implies.
* Well, high current flow through a wire results in a lot of waste heat being generated, so I suppose, technically speaking, a high current could be dangerous in that you could be burned by it.