The point is basic: in Islam, money should flow from the rich to the poor (hence the pillar of Zakāt, or almsgiving). Interest doesn't really do that under basically any circumstances.
Sure it does, in its most basic point: lending. The most basic assumption of borrowing is that leveraging future purchasing power now rather than later leads to profit opportunities for both parties.
The only reason why that isn't necessarily the case is because 90% of people haven't given a thought as to how interest works and they just treat it as free money, and end up getting burned.
The cultural prohibition against interest is in my opinion perhaps one of the greatest factors in stalling the economic development of the Middle East.
Pity is, it's the wealthy in the Middle East who are the most likely to ignore those prohibitions. The poor don't have access to those mechanisms, and are more likely to be pressured and ostracized.