[Sleeping Beauty]

Part two of the question is the most important:

....and why it [the World Bank] is so important to our US economy and US-based multinational corporations?

It helps to read the article and think about why there are so many Wolfowitz "camps" in the White House.

And, here's a secret-decoder clue:

Wolfowitz wanted to clean up corruption in the government of the borrowing nations (not at the World Bank, BTW). Why is it in the World Bank's interest that those borrowing nations have corrupt governments?

[EagleUSA]

Why is it in the World Bank’s interest that those borrowing nations have corrupt governments?
:::
There is probably a multitude of answers to that question. Let us have yours. But I would say that there is definite advantage if the sourcing, use, costs and amounts of monies sourced by the World Bank being kept quiet, or incorrectly reported...can be easily bought and had. My gut feel, anyway.

[PAR35]

and why it [the World Bank] is so important to our US economy

It isn't.

and US-based multinational corporations?

It funds infrastructure so that the multinationals can build factories to outsource manufacturing jobs, so they can close higher cost facilities in the US.

Wolfowitz wanted to clean up corruption in the government of the borrowing nations

Given his personal actions (giving other folks money to his girlfriend, rather than his own), I don't really accept your anti-corruption premise.

[CutePuppy]

“....and why it [the World Bank] is so important to our US economy and US-based multinational corporations?”

Think of UN’s Oil For Food Fraud - a lot of corporations couldn’t legally or “legitimately” do business with Saddam, without UN OFF programme cover. WB is even better than UN as it provides not only cover of legitimacy, but it practically guarantees profit because any potential losses are underwritten by US taxpayers.