Feudalism has more in common with communism than capitalism.
I think you are mistaking the heirarchical nature of society with our current socio-economic system. As it turns out ALL societies are heirarchies, from ancient Sumer on down. I think it may be ingrained in us humans, as in most other species, to have alphas, betas, omegas, etc. The cool thing about capitalism is it's the easiest system in which to buck the heirarchy! Any one can start out dirt poor, and make themselves successful, and often wealthy. And you don't have to be ruthless to do it. All it takes is one Great Idea, and you can sell it to anyone willing to buy it.
In feudalism, if you are born into a class, you spend your entire life as a member of that level of society, period. No matter how talented, creative, hard-working you are, you are guaranteed no upward mobility. If your a serf, the lord of whatever area you live in owns you. You can't leave, you can't keep your crops to yourself, you can't build yourself a new house without his say-so.
If anything, capitalism, even with all of its problems, is like an Anti-feudalism.