Granted, you have the right to carry concealed and thus should have the right to open carry.
Actually, the opposite is more true. The SCOTUS in
Heller highlighted that laws against concealed carry were typically upheld where open carry was historically protected.
I believe the CCW case law history evolved from older societal customs which dictated that hiding one's gun was underhanded, sneaky and somewhat dishonorable.
Today, because it's much less common, open carry of a pistol is seen more as rude, or worse, threatening. Since 37 states (or whatever the number is presently) have enacted shall-issue CCW licensing, the 'norm' is now to conceal.
But if open carry is not allowed, there emerges a variety of potential pitfalls to the CCW-only regimen. Some have already been mentioned such as inadvertent exposure of the weapon.
Other problems may include a sudden need to carry a weapon when no suitable clothing is at hand to sufficiently conceal the gun. It is possible to imagine any number of plausible circumstances and reasons why open carry can not, and should not be prohibited, starting with the fact that it is historically, and presently, IMO, a fundamental right.