Good questions.

• yes there would be need for a lot of insulation at high current except that we won't need so much spaces in between the insulators. Because air is an insulator, we won't require as much spaces between them as we have in high voltage.

• like a saying that it is current that kills not the voltage. Which happens to be correct to 90deg. So if the operating current is high, and we experience a fault on the line and it happens to fall to the ground, casualties might increase drastically. We will also put operators life at danger incase of a switch because of the amount of current present in the breakers.

• tower height might not be that much.

But in all, safety has to be considered first above all, and the high voltage offers more of that. The advantages of high current doesn't outweigh the disadvantages.

Thanks a lot for stopping by