This editorial appears on Bloomberg View.

Once upon a time, President Donald Trump vowed to "do a very major haircut" on the Dodd-Frank Act. After a lengthy review, his officials have apparently concluded that the 2010 law's approach to the failures of large banks was about right. In some ways, this reversal is a pity.

The 2008 crisis showed how dangerous it can be to let a big, interconnected financial institution go bust. When the U.S. tried that with Lehman Brothers, the repercussions were disastrous. Within months, the government was supporting vast swathes of the financial industry, including money-market mutual funds, AIG and the country's largest banks.

In response, Dodd-Frank created a tool aimed at making big failures more manageable. Known as the orderly liquidation authority, it allows regulators to keep myriad operating subsidiaries running -- with the help of government loans -- while shoring them up at the expense of the parent company's shareholders and creditors. Ideally, a newly recapitalized enterprise emerges.

The mechanism has flaws. It's untested, for one thing, and it's unlikely to work in a full-blown crisis -- when multiple countries are involved, markets are volatile and nobody knows exactly how insolvent financial institutions really are. It might be able to handle the failure of a single bank in otherwise favorable circumstances, but anything bigger would probably require a blanket government guarantee to prevent panic.

Yet even if this part of Dodd-Frank could be improved, the Treasury Department's review has come up mostly empty. In a 53-page report, the biggest proposal is to adjust the bankruptcy code so that it's better fitted to financial institutions -- by adding features similar to those of the orderly liquidation authority. The Treasury also suggests changes to the authority itself, but these are mainly cosmetic, intended to make the mechanism look less like a bailout.

The effort illustrates, once again, the crucial point: There's no good way to let a systemically important financial institution fail. That's why it's vital to make such failures as unlikely as possible, by requiring institutions to have enough equity capital to absorb even severe losses. In this, despite improvements since the crash, the U.S. still falls short.

It's good that regulators have a plan to handle big bank failures, and that the Trump administration isn't planning to simply scrap it. Ideally, they'd do more to ensure that no such plan ever has to be used.