I have no problem with the idea that Earth is a paradise of sorts, and even if a group of people don't like living on what pretty much amounts to a socialist Earth, there's hundreds of habitable planets in Federation that those people can settle on to get away from Earth. The near-utopian Earth isn't a problem for me, Earth is but one planet, we hardly ever see it in the shows. So long as the frontier of deep space has interesting things going on then Earth can be the most boring planet in the universe for all I care.
What's a problem for me is that Gene took his ideals to crazy extremes. For example, I've heard that in the original script for BOBW
Picard was going to have his arm lopped off and replaced with a Borg arm, and once he was rescued he would get a replacement arm that would be indistinguishable from his real arm. Gene shot it down on the basis that in the future people's limbs wont be amputated.
What the hell?!
Because Earth is a paradise that means that accidents can't happen? People can't lose their limbs in combat? The Borg, a soulless entity determined to assimilate the galaxy, would adhere to Roddenberry's utopian principles as well? That makes absolutely no sense. It's idealism gone mad. It's also one of the reasons why Ira Behr had to fight Berman for Nog to lose his leg, because Berman was trying to protect Gene's vision and Ira Behr was trying to tell a good story.
Earth was said to be a paradise, no war, no poverty, etc. This is the whole idea of the franchise.
How did DS9 contradict this? There's still no poverty or war on Earth in DS9.