Well, existing inequality doesn’t go away on its own just because material conditions improved. First, they aren’t improved enough to solve all the issues on their own. Second, under capitalism the wealthy are benefitting more from those improvements. And third, previous attempts at moving away from capitalism all either got taken over by dictators and turned into state-sponsored capitalism (see USSR and China), or got backstabbed and crushed by aforementioned state-sponsored capitalism (see various anarchists communes of 20th century). We’ve gotta improve material conditions and eat the rich.