Minecraft is a game for all ages, while this does not nescessarily mean that mods shouldn't include violence, you must still keep in mind that children will unconsciously see what you make as a blocky representation of the outlines of reality. With that in mind, you must be conscious of a few things:
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Resources are not unlimited, much like on Earth. For example, let us suppose a tech mod implements hydroelectricity - such a tech mod should also make an effort to show the side-effects of such an energy choice, e.g. making every connected water source in a designated chunk radius be harmful to the player, or de-leafing all trees in a radius, etc.
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Non-violent solutions are rare. This isn't the place for your moral tirades; punching back the bully is an appropriate course of action. Non-violent solutions for passifying hostile mobs should be rare and should be based on natural phenomena if your mod includes a real-life animal. For example, wolves are neutral and only friendly upon taming.
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Every game has an ideological aspect to it, but not nescessarily a partisan aspect. Including the real-life names of any organizations or even obvious references should be avoided, unless your mod involves geopolitics. Trying to create "fair" depictions is normally just creating depictions that support the status quo, remember this: your work is propaganda once it includes partisan aspects.
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Fauna degradation should be noticeable. Minecraft does this by not respawning passive mobs. However, it's not unreasonable to, for instance, make it easier to repopulate passive mobs.