Ponder this: The very idea that citizens may be carrying concealed serves as a deterrent even if nobody chooses to exercise that right.
I have heard this plenty of times, and there is certainly a logic to it. However in reality I do not think it has an effect. These are typically short sighted opportunistic criminals, and thinking about what a tiny percentage of the population might do is not likely to deter them. Concealed carry is a statistic that is unseen, and unlikely to be noticed by those not looking up that statistic.
Concealed Carry also does little to promote gun rights, nobody gets familiar with being around guns, or must face the reality that there is guns around them every day. They retain anti-gun beliefs and spread them, 'safe' in their own perceived reality where guns in public are rare and a threat when present.
It benefits the individual carrying, but has no effect positive or negative on the views of society outside of those who are themselves carrying.
Open Carry on the other hand once it becomes accepted causes the population to be well aware of guns present on a regular basis which are posing no threat and are being used responsibly.
This makes it difficult to retain certain anti-gun beliefs faced with the reality of guns all around you on a regular basis.
People are confronted with their beliefs as they see guns being carried, until they no longer have an emotional reaction to seeing holstered guns.
A population accepting and used to open carry is also one where banning guns becomes quite difficult, and gun rights expand.
Arizona being a prime example, before Constitutional Carry where anyone could carry concealed or openly with no permit, they had open carry a normally observed thing (because it required no permit like concealed carry.)
This is quite likely what allowed the state to progress to Constitutional Carry.
Additionally Open Carry confronts news citizens like say California transplants with the reality regularly, so they can adjust gradually in small numbers as they move there rather than ban guns as a unified voice after relocating in great enough numbers.
Open Carry once generally accepted has a strong pro-gun effect on societal views, while Concealed Carry has nearly no effect. Although initially Open Carry can have a backlash anti-gun effect, once acceptably established the pro-gun effect is significant.
So while Concealed Carry may be preferred strategically, Open Carry should not be derided, it being a normal accepted thing benefits us all.