Step-up basis is important for anyone who inherits property from their parents. That can be substantial in places like California where real estate has gone up a lot.
And for inherited rental property, there is another huge loophole: you can can depreciate the full market value of an asset that you got for free. That’s a substantial tax benefit for many years.
The step up basis makes sense in a world where you still have to pay substantial inheritance taxes. But with minimal to no inheritance taxes, the step up is a giveaway.