Why don't officers wear marksmanship badges?

well i see a CIB medal and thats all you really need---

Simply put; officers DO regularly wear marksmanship badges. The OP left out the distinction that this is an “Army thing”. I would bet that it's primarily a 'cultural' thing. Army leadership prefers certain optics regarding the appearance of their officers. The uniform and how it is worn sends a non-verbal message to those who view it. "Big Army" has their reasons. (But talk to 5 people and you might get 10 different opinions.)

I can imagine or speculate a couple different reasons for it, but I personally hold the opinion that the badges should be worn for at least two reasons.
1) To display that you are qualified to handle a weapon (probably the most basic of military skills).
2) Because you'd have it on display for the world to see; it creates an incentive to be more than just competent in that skill.

Yes! I think officers should wear marksmanship badges...

During my service, active and reserve, (1960s-90s), Infantry and Field Artillery units, I always wore my marksmanship badges along with other awards on my greens. Why would you not? Maybe in some units there may be a culture thing about not wearing certain awards depending on rank but that is new to me. this may be similar to the culture in the Infantry in Viet Nam that you didn't put in for a Purple Heart unless your injury was serious enough to require a medevac. This was a reaction to a couple officers at the Division TOC who, while on duty, were across the road drinking at the Officers' Club and when there was a rocket attack had to crawl back to the TOC across a gravel road, tearing up their knees for which they got Purple Hearts. We grunts in the bush were pretty unsympathetic.

Officers of Marines wear their marksmanship badges.

Before I was in the ARNG, I was a Marine Captain. Marine officers always wore marksmanship badges when possible, as did all Marines. I continued while in the Guard. Earned them and wore them…

All this word salad about collective vs individual Soldier responsibility is BS. An Officer must master their profession of arms. An Officer leads by example. That includes being an expert marksman. AND so all that other stuff. Officer generally breath a sigh of relief about not wearing the marksmanship badge, because they can’t shoot expert… because they don’t train to shoot expert. Tell me how much respect an Officer earns as a mediocre APFT performer, or who falls out on a run.
In my Battalion, every Officer wore what they earned. They showed all Soldiers what their current competency in their shooting craft is. It’s a perishable skill.
Enough of this weasely rationalization. Sounds sage, but if you gotta talk so much to explain it…probably hiding the obvious.

Marine officers are proud to wear marksmanship badges, always do, and are almost embarrassed if they're not sporting "expert" pistol and rifle badges on their "Alpha" uniform jacket. It may be that US Army officers do not generally wear them, but US Marine officers always do. The old saying that Marines quote often, "Every Marine's a rifleman" and the Marines' shooting heritage is partly the reason why this is so.

If you earn them, wear them, pretty simple.

My old Brigade Commander would wear his badges. It's just not commonly done with officers.