Many poets choose to write poetry for political, social or philosophical reasons. These poets have a specific point-of-view that they want to express. There is nothing wrong with writing poetry to express a viewpoint, but I have found it often results in poetry I have no interest in reading.
I do not want to be told that the genocide in Sudan is deadly and awful. I already know that it is. I do not want to be told that child abuse is terrible and hurtful. I already know that it is. I know that war is terrible and I know that it is sometimes necessary. I know that people can be hurtful and they can be kind. Most people understand these things.
I am not telling you what you can or cannot choose as a subject. Write about Sudan. Write about child abuse. Write about war. Write about cruel people or happy people. I am willing to read a poem on just about any subject. The key is to focus on the details, not the general point. The poem will fly or plummet based on the details. If you want to tell a story about a war, focus on a single moment, person, or visual. Dig into the details of your subject.
I do not want to read a poem that tells me war is bad, but I might be interested in a poem about a truck that has survived a war — a poem that describes the dents, the scratches, the burn marks on the surface of the truck and how each mark got there. Those are the details of a poem. The point of a poem is usually expressed best when it goes unstated and readers draw their own conclusions.
The key is that no matter what the subject of a poem is, great or small, the goal of the poet should be to make every part of that poem as interesting to the reader as the subject is to the writer. Blanket statements can kill a poem. The same is true of overly obvious or overblown images. Often, when people think they are being dramatic, they are being melodramatic. This is another case of focusing on the subject rather than the details.
When developing an image, make it a goal to veer away from emotional descriptions and look for literal descriptions that match the emotion. Compare these two lines from my hypothetical war-torn truck poem.
The angry bullet hole was dark and frightening
An irregular circle burn surrounded a bullet hole close to the driver’s door
While I am not claiming either line is art, the first image aims for an emotional effect and (I think) fails. The second line keeps emotion from the overt description, but demonstrates the menace involved. I am not saying to keep emotion out of your poetry, just be mindful that your readers would rather feel something on their own than be told to feel something. That said, there is no doubt the second line carries emotion. The words burn and irregular evoke negative emotions and the location of the bullet demonstrates the possible consequences of the shot. The line is more subtle, but it still creates an emotional effect.
Writing a poem that sets out to express a particular idea or opinion is difficult and often unnecessary. You already have a point-of-view, and it will come out in your poetry. You do not have to set out to tell how you feel or what you want people to understand. If it is inside you, it will show up in your poetry. All you have to do is keep writing.