Wearability for the jungle is one of the reasons but also there are a few others. The "ho chi minh" sandle named because supposedly ho chi minh came up with the idea. The sandles themselves are very well made.
They take a old motor bike, or car tire and cut out a foot print and then use the inner tubes as bindings. This makes them not only very very cheap to make but also quick to repair and no shortage of materials. Very easy and quick to put on but with no detriment to the food when walking. (they are very comfortable) They also used the foot print to trick the American soldiers as they used to turn the shoes round the other way. This would lead the Americans into thinking the trail of footprints they had picked up was heading one way when if fact they were heading the other.

I would like to add a side note to say that I had two pairs of these when I was out there and they were amazing. I could run walk, grip, climb and swim in them without them falling off. And they were my footwear of choice whilst in that climate. I was devastated when I lost them.

https://upload.wikimedia.org/wikipedia/commons/2/29/Tire_Sandals.jpg