This is different from parent leaving you stock and bonds.
Father dies, leaves company that makes engines to son and $50 million in cash because he has invested most in his company. IRS+State: son, you owe us half+ of what your father left you, or $1.1 Billion. If he borrows half of company's worth that's not going to be a healthy company anymore. So he sells it and selling is not always the best thing for employees.
Edited: If I was made King, I'd look to lower the inheritance to children to say 10% and abolish trusts that fund generations of lazy, spoiled brats living from their great-great-grandfather's money.