Why should a society be structured by majority rule / majority benefit for such things, even if one agrees with your premise that society is supposedly better off (which I disagree with, you're not counting all the required consequences that go with re-ordering the system, you're pretending we're only talking about one thing)?
Actual democracy is an extreme negative, not a positive approach to organizing society.
You can claim the majority would benefit from eating the wealth of Sergey Brin and Larry Page at this point, they no longer operate Google, they're just ~50 year olds sitting on $200 billion in Google shares, piddling around until the day they die. So why not let society benefit sooner rather than later by consuming their wealth to its (supposed) benefit, divvy up their wealth to the poorest 51%.
You can invent a huge number of scenarios for doing things like that, where society supposedly is better off if we violate the property rights of some minority group. Why shouldn't some minority of people be allowed to lend at 43% interest if there are takers at that rate? Because you say so? Why shouldn't their property rights be respected - the property right to lend their money out at the rates they can command - and why should the majority get to arbitrarily restrict their property rights? It sets up an obvious exploitation situation, which is always the case in democracy, where the majority can endlessly torture, exploit and abuse the minority.
It would very clearly be better for the top 51% (far more than that actually) - the majority of society - if the economic bottom 10% did not exist (a group that rarely holds a job, has vast health & drug addiction problems, rarely pays taxes into the system, rarely contributes much of anything; and in fact that's true in nearly all welfare states, including the US). So they should all be gotten rid of, is that right? Democracy in action. The tax paying majority is sick and tired of carrying the never-tax-paying economic segments at the bottom, time to get rid of them, for the benefit of "society" (aka the majority power herd).