All interest is usury in Islamic Law (and the laws before it such as Christianity and Judaism). There are ways to to put free cash into productive use without exploitation.
If going by the very poor economic performance of Muslim countries I would say interest is a very good thing if limited to reasonable interest rates and fair bankruptcy laws.
Correlation vs causation (post WWI colonization comes to mind, that continues to this day). Historically, there was a period of time when there were no poor people left to take Zakat, everyone paid their share, and no usurious transactions permitted.
Historically, there was a period of time when there were no poor people left to take Zakat, everyone paid their share, and no usurious transactions permitted.