Forcing viable businesses out of business because the heirs cannot pay the estate taxes without selling off the assets is a loss to the country, as well as an unjust burden on the individuals concerned. Moreover, people have foresight and one of the reasons they work and sacrifice is to see that those who are dependent on them will be taken care of after they are gone. Destroying or undermining that incentive is sabotaging a virtue that is as important morally and politically as it is economically. Those who want a society where everyone depends on government for their needs may be happy to see yet another blow struck against self-reliance. But no one else should be.
Luck certainly plays a very large role in all our lives.
But we need to be very clear about what that role is. Typically, they have it because their fellow human beings have voluntarily paid them for providing some goods or services, which are valued more than the money that is paid for them. Luck may well have played a role in enabling some people to provide valuable goods and services. Others might have been able to do the same if they had been raised by better parents, taught in better schools or chanced upon someone who pointed them in the right direction. But you are not going to change that by confiscating the fruits of productivity.