Don't youse all remember Mr Haughey's little contribution. If you owe the banks €1,000, it's your problem. If you owe the banks €1,000,000, it's their problem.
If you're a high net worth individual, a lot of your wealth might be tied up in illiquid assets like pensions, stocks and shares. Could be expensive and drawn out to get at that money. Might be easier for the banks to take half or 1/3 of the debt in cash and take the problem off the balance sheet.