Rikers Island is a cesspool of violence, corruption and incompetence. But Mayor Bill de Blasio has dismissed the idea of closing Rikers as expensive and “complicated.”

This is the mayor who is promoting a big, expensive plan to bring a streetcar to Queens and Brooklyn; who pushed for universal pre-K and an overhaul of the city’s handling of mental health. De Blasio has been the mayor of big ideas and even bigger promises. And yet, when it comes to Rikers, he virtually closed the door to a potentially sweeping solution to a deeply rooted problem.

His answer must not be the answer. City Hall must welcome all ideas, starting with the commission to be headed by Jonathan Lippman, the state’s former chief judge. It will review the system, including the possible closure of Rikers.

Rikers has about 10,000 inmates, many of whom can’t afford bail or are awaiting trial. Violence plagues the facility. There are regular reports of corrections officers attempting to smuggle contraband, such as drugs and weapons, inside.

Then there are the stories that should shake us to our core. Andy Henriquez, 19, died in his cell in 2013 due to a ruptured aorta, months after he complained about chest pain, according to court documents that outline insufficient medical care. Jerome Murdough, 56, died in 2014 after his cell’s temperature spiked to 101 degrees, while no one checked on him. And Kalief Browder committed suicide last year, at 22. He had been accused of stealing a backpack and spent 3 years in Rikers, much of it in solitary confinement, without standing trial. And there are many others.

City officials point to fixes they’re working on, like eliminating solitary confinement for young inmates, decriminalizing minor offenses, changing bail procedures, and new recruitment, screening and training strategies. Those can help, but aren’t sufficient. Rikers needs intensive structural changes — to its procedures, its personnel, and its culture. It needs a commitment from all parties, including the Correction Officers’ Benevolent Association.

What’s been done so far has barely made a dent. No one has all the answers yet. Don’t dismiss potential ones.