they are very very useful, keep the delicate innards of the arduino from touching your workspace which could have conductive things or dirt or spilled soda
i strongly recommend they are added to arduinos in the future. only costs maybe 10 cents.
good thing, cuz i noticed that if i rest my fingers on the bottem of the arduino, in certain places, it messes with the code, for instance it can stop the code, and when i let go itll keep going, or the code will just flip out!