To quote Keynes, ironically, "in the long run, we are all dead", and even wealth that gets passed on to children is frequently frittered away. There is no guarantee of unending passive growth if society at large does not make productive investments. Plenty of countries have learned that the hard way. I think this is a bias of modern westernized countries for the last century.

"The economy improves and so assets do become more valuable, inevitably." More pricey, no guarantees about more valuable though. Some assets may be entirely Ponzi-like and have little value, but a high price.

And anyway, if the economy is improving, homeownership / rent would be more affordable, families would only need one parent to work, the number of hours worked to buy S&P500 would be more reasonable, things like healthcare and education would be getting relatively cheaper. But artificially cheap margin debt, speculation, and financial chicanery backstopped by the central bank have lead to a lack of productive investment. Unusually high immigration and population growth without a corresponding increase in productivity causes higher prices too. Everything is getting harder from the point of view of Mr & Ms NoAssets 20-somethings who earn a wage.

The fixation of the tax-happy is on making the rich poorer in a dollar-net-worth sense. But there is no focus on making the poor richer in a purchasing power sense (what you can buy).

This requires a gradual deflation, higher reserve requirements, saving and careful investment. All currently very unpopular with the asset-rich, banker class, and thoroughly captured mainstream economics profession, who want you drowning in debt buying ever more expensive stuff, and not deferring consumption to the future.