Some bubble caps have an angled cut on the spout, is there any functional reason for this?

If the tube is straight but cut at an angle this is for aesthetics only.  The air needs to come out at an angle to get the terp pearls to spin.

In the image below you can see the tip is cut, but the air will still come straight down.

As you can see in the image below the air is now coming out at an agle, this will cause the air to spin more and spin your terp pearls and oils.