When one reads the Koranic references to riba, particularly Koran al-Baqarah 275-280, there is usually a reference to injustice, exploitation (ie "redoubling") and the benefit of charity. Riba embodies an element of injustice and unfairness, and this is consistent with the emphasis in Islam on social justice. An interest charge in a competitive market representing a reasonable amount for time value, illiquidity, and credit risk cannot be regarded as exploitation.
The mistake is committed by those who ignore the fact that money has time value - an accepted principle of modern finance. This value requires compensation - interest. Many conventional Islamic scholars have asserted that money is just a medium of exchange. But it is more than this; it also represents productive capital. Money can be used to purchase productive assets such as real estate and capital goods that earn a return.
This view is at variance with much of the conventional Islamic approach (but not all - see the fatwa of mufti Tantawi on bank interest, Al Azhar University), but it would not be the first time the conventional view is wrong.