Mr Abdel, "why not" you ask. Well the "world bank" declares itself to be a banking and development expert for the entire world. Declaring that one particular religion has a specific cure for building an inclusive financial system to help reduce poverty thus already for this reason seem extremely dangerous. Furthermore, it ignores the entire system (of the 3 Ibrahimic religions) in which the "Riba" provision was pronounced by the prophet (MPBUH). And finally it ignores the lack of evidence and an increasing list of cases of failure and corruption within Islamic financial institutions.
The promotion of Islamic Finance without proper religious understanding and without factual evidence is thus dangerous. Already articles are published of the political use of this "micro-finance trend" by organisations such as the Islamic Development Bank and the Qatar Fund.
Finally Mr Abdel, we all know that poverty is highest and most widespread in relative terms in countries where Islam has a strong influence on politics, economy, the legal system, the entire lives of their citizens. So reasons plenty to state that the WB is acting in a very imprudent and opportunistic manner.