So you ask, “Why is this so important?” The downspout carries a tremendous amount of water from the the roof during any rain or snow event. Ideally, you would like this water to drain away from your home as quickly as possible. Even a small amount of water that pools around the foundation will find its way to the bottom of the wall and depending on the condition of your footer drain, maybe into your basement. I have inspected dozens of homes that the water runs under the block and into the basement every time that it rains. This makes it difficult to finish a basement on the interior and not end up with a mold issue.
The other result of the water pooling at the foundation wall is hydraulic pumping of the soil. This results in the clay that is in the soil expanding and putting pressure on the foundation wall. If the wall of the foundation is mostly underground, this can result in tons of pressure that pushes the blocks inward. There is usually a horizontal crack with stairstep cracks on each end that indicate this is/has happened. This can turn into a serious and financially painful problem. The price to excavate to relieve the pressure and repair the wall is very expensive. I have included a picture of a downspout discharging at the foundation wall.
Do yourself a favor today and make sure all your downspouts are discharging away from the foundation and draining away from your house.