The question is not whether it was a better or worse world or reality. The question is why those who rebelled against House of M reality believe that this was the right thing to do?
Yes many had what they always wanted and in general the world was better but that does not mean that the world was what it should be for those who rebelled. Basically we are talking about human nature where right and wrong or concepts about how the world should be vary from person to person. In that sense for some it is not enough to have what they most want if they do not make it happen for yourself or through hard work. For some the journey is more important than results.
If you look at the reality created by the acts of the apocalyptic brothers in Uncanny Avengers the X-mens had what they always wanted and yet they gave up on this to save humanity. The reality created by Cap's Hydra version had world peace but with a view that the heroes disagreed about the world and they fought against it.
In the same way the Phoenix 5 were creating a better world during AvX ending hunger, wars and giving energy for free but the Avengers and rulers of the world were not satisfied or they thought that was wrong.
For example if you create a world where humanity is immortal and does not age or need to eat some would call paradise or eden since wars would end. But others will think it would be a wrong world where humanity would be stagnant without change or evolution in this world humanity would not need procreation and would probably lose its spiritual side.
Even though you are God and create a perfect world human nature will challenge this concept because they have that choice
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Now on mutant utopias they will always have elements in common with House of M but that does not mean they need to be the same.