To be fair, there's been lore showcasing exactly how dark Demacia really is, behind their gilded spires and claims towards honor and justice. Lux' old League Judgement being the best example of this. The problem is that it's lore that's been hard to find, more or less hidden from the people who didn't know where to find it.
http://leagueoflegends.wikia.com/wiki/Lux/Background
Scroll down to the "League Judgement" section and have a read. I think it's fair to say that Lux looks like she's one of the most cheerful and happy of the champions in the game, but behind the happy mask she tends to wear, there's something far less so hidden beneath. She was torn from her home, her family and friends at a very young age, her parents thinking only of how great an honor it would be to have her admitted into th academy. To them, it was done in the king's name, and that was all that mattered. The fact that the young girl barricaded herself in her own room, and had to be forcefully be dragged away meant less than nothing.
She cried herself to sleep every night, cursing her family for doing such a thing to her. The only thing that ending up giving her a meassure of comfort, was reading the Meassured Thread, which I'd assume is a summation of Demacian ideals. She was more or less being indoctrinated into serving and loving her country. Perhaps the saddest part is that she's aware of it herself, highlighted by a paragraph in the Judgement "The absolute love for her country. The emptiness of realization of what she had willingly grown to love. "
The following is sorta non-canon given that the League has been retconned out of the lore, but the way she's described as feeling, is more likely still accurate:
_“Will you admit the real reason why you want to join the League now?”
Her labored breaths caught in her throat just long enough for her to whisper, “Because I have nothing else…”
The darkness shattered around her, falling to the ground in shards. She crumpled to the ground, heaving sobs racking her body. _
She's not a happy young woman, despite what she wants to show the world. She's been horribly treated by the the other side of Demacia, the part they'd rather keep hidden behind the image of good and justice they like to claim. The worst part is, you more or less have to assume that her story isn't an isolated one, that this could be a very real thing for much of Demacia's youth. Being torn from their homes, and indoctrinated into serving and loving their country above all else, even over the wellbeing of their own family. Demacia might've done less overt evil, they've never invaded countries like Noxus have(That we know of), they might frown on some of the things Noxus is willing to do when it comes to winning.
But at the end of the day? They are, quite frankly, not much less evil than Noxus, they're just more insidious in their particular brand of evil, keeping it behind the scenes. Noxus are entirely open about what they are, they hide nothing. Demacia is the opposite, where in Noxus everyone can gain anything if they have the abilities, in a sense the ultimate idea of freedom, Demacia instead takes away all freedoms, choosing for their citizens, working on them until they conform to the standards the State expects of them.
Does either place seem like a place you'd want to live?
