The prohibition against the taking of interest, is viewed as a very severe violation of the Torah. The damage is not seen immediately, but in the long run, the recipient of a loan with interest, may never get out of debt.
This idea is seen in Pirkei Avot, where there are parallel positive and negative characteristics are mentioned. There is the idea of a good neighbor and bad neighbor. A good friend and a bad friend, where one must always choose towards the good.
After this, there is another pair of good and bad. The good is רואה את הנולד, to always look ahead and see the consequences of our actions. The negative side of this is לווה ואינו משלם, taking a loan without having the ability to pay back this loan. This is very much connected to the prohibition of taking interest.
There are many instances where an individual gets deeply in debt, and goes on a spree where he continuously borrows from one to pay the other. The problem is even greater when interest is added to each loan. It becomes a bottomless pit of debt.
The Torah understood this reality, and, at least, tried to ease the burden by at least making it clear, that taking interest is out of the question.