I mean the realistic (self-consistent) answer is that you can't cure the society's ills in your off-time. Not even by killing people (though it may be marginally more likely to succeed). As far as not killing civilians it seems that people owning slaves, people oppressing people for having different religion/physical features/partners, and corrupt jerks who hoard wealth are more likely to be civilians.
As far as Wh40k goes I think that violent shortcuts are usually presented in two ways. Either it is a grim necessity ensuring survival, "Men must die so that Man endures", or it is darker option of "you'll learn to love the taste of this boot" (Imperium are not the good guys, after all). Where each individual instance falls is up to debate. This does not help your cause because even theoretically the fact that some means are allowable in extreme circumstances (survival) does not mean they are allowable for each and every good cause. You also can change a lot of things outside of what the GM's wants you to focus on, without being able to change anything you want. There are a lot of things which cannot be done or reliably done.
IMO a character who is focused on creating beauty is nowhere guaranteed to create a most beautiful artwork in history (even if it is a long campaign and player sinks some resources into making the character a good artist). If you would expect for the artist character to do this then maybe a social-oriented character should be able to reform the society; we just hold different ideas about power and effect of "average" PCs. But if you will not say that about the artist character then you are one expecting success of character's schemes to depend on how good or desirable or enlightened their goals are. And with character who is not socially oriented you will likely have either no result at all or aforementioned military dictatorship if they are good at applying their violence (all in the name of freedom from oppression, of course).
I would love to see more unconventional gender signifiers, especially given how things were different IRL in different times and places (manly man kissing each other on the mouth, societies where openly crying is seen as a sign of sincerity or humility), but in fantasy I think some norms (which need not to be gendered) are expected or it all ends up looking like a ren fair instead of an actual society (ren fair fantasy is acceptable but not my default assumption for a setting).
As far as celebrated vs acknowledged I do not think it universally holds true. In the XIXth century and earlier literature a lot of time was spent on people struggling with class divisions and while class divisions remain the particular elements has disappeared, particularly the importance of (formal) nobility. A lot of those stories will not work if background changes to the late XXth century. Struggles of "commoners" who may have education, manners, money to achieve recognition; struggles of aristos to keep up appearances even if they know it's suicidal in the long term - they doesn't quite translate.
You view e.g. corrupt jerks hoarding wealth as imminent disaster allowing non-judicial killings? Or because there is an outside disaster waiting to happen you can shape the society by non-judicial killings (and without that threat you'd be more careful with your means)?