I mean, the Equalists are RIGHT. They're right! THE BAD GUY IS RIGHT. Also Amon is terrifying.
Wanting to get rid of the people who built the city, provide all the electricity, police the city and are the center of what seems to be the most popular entertainment for the people doesn't seem like the right thing to do because it isn't. Benders certainly aren't the cause of every war like Amon said and they typically felt the brunt of the last war, ie the genocide of the airbenders, the oil rig earthbender prisons, and the hellish prisons they kept waterbenders in. I'm pretty sure the earth king wasn't even a bender, or at least never showed it, so nonbenders are in positions of power. Also consider that if Amon can energy bend he should also be able to make all people benders if he really wanted to.
As always it is all about balance. Everyone has there place much like Sokka in the original group. Actually, Sokka being a non-bender with the avatar is extremely important in retrospect now that this season has started.
I don't think a spirit would burden themselves with the happenings of the real world. Not to sound like a jerk, but I hate all the theories throughout the years of him being behind a bunch of stuff.
Plus, Amon's claim that he is being led by the spirits is probably an utter lie. Same with his supposed "backstory". Probably just propaganda for his cause.
The spirits are connected to the real world though as we saw throughout the original show. They would have no desire to do something like rule the world as many crazy fan theories say but I find teaching a man to energy bend to be very possible. I too hated those theories as I find that people being the villains is much more compelling and I expect Korra to have men be the villains again with spirit involvement in some way much like the original show.
The spiritual side of things is obviously going to be very important in this show considering the emphasis we see put on it. We don't find out Korra can't airbend until well after we hear that she has difficulty with the spiritual side of bending several times. The first time Tenzin is talked about he is mentioned as "Mr. Spiritual" not the only airbending master in the world. Korra can't even meditate right now. I predict that much like Aang learning the elements we are going to see Korra learning about how the Avatar is the bridge to the spirits considering how many times it has been mentioned and this is what will help her restore balance between benders and nonbenders.