As I understand it, if a single person has assets below £325,000, no Inheritance Tax is payable. Married people or people with a civil partnership need to have assets over £650,000 before IT is payable.
I certainly want to leave money to my children and grandchildren but I don't think it's unreasonable for Inheritance Tax to be payable above those amounts - it still leaves a substantial inheritance "pot". Not all young people are fortunate enough to have money left to them and I think it's right that some of the money goes back to the government for re-distribution. If it doesn't, some families just accrue more and more wealth by virtue of the hard work of previous generations, rather than their own hard work.
As Frank says, if money/shares, pushed total assets above those limits, I suppose they could be gifted to children before death. It must be tempting to do that though some might think it unethical. I imagine the tax people would be interested in large amounts of money being disposed of prior to death.