Is this the feeling of other uncircumcised men? Does this mean that you consider the glans to be a a very private area and that you are modest about having others see it? I infer from your post that you consider having the doctor see the penis with the foreskin covering the glans to be one humiliating experience and then having him see the glans after the foreskin is retracted to be a second humiliating experience. Is this a correct interpretation? I have thought for a long time that one of the interesting aspects of circumcision is the fact that it exposes a part of anatomy that was intended to be covered and concealed. It seems so strange that circumcision has become such a cultural norm in the U.S.
In cultures that do not practice circumcision, which incidentally to put things into a historical perspective, has been the overwhelming majority of cultures throughout the world, retraction of the foreskin is usually a prelude to some kind of sexual activity. It's an indicator that the male at least has an expectation of sex. And when a partner does this for a male, that is an even greater indicator that sex will happen.
But in a medical exam situation, a doctor deliberately retracts the foreskin, not to initiate sex of course, but as part of a medical activity. In modern terms you could say this is a mixed signal. Of course the examinee knows that there is nothing sexual intended, but even so, physically and subconsciously, for some males the body probably has difficulty processing these signs. So there is a conscious knowledge that it is being done in a non-sexual situation, but subconsciously the body may react as if it were a sexual situation nonetheless. The discordance between the two can give rise to any number of feelings: nervousness, bashfulness, humiliation, or just as well arousal anyway, often as is recounted here in the form of post-examination (masturbation) fantasies.
Why some cultures embrace circumcision as a cultural norm is not always completely clear. Pharonic Egyptians were thought to have been amongst the first to do so, but then probably only at first for priests or temple attendants as a form of initiation or a way to remain pure in some ritualistic manner. Circumcision lessens sensitivity of the glans and hence can be thought to diminish sexual desire and sexual purity can in some religions be thought to be a desirable state and pleasing to whatever Deity is worshiped. That's one (religious) explanation for the origin of circumcision, though one can just as well argue a number of others.
In the US, it is probable that circumcision became a widespread phenomena due to what can be called a Masturbation Scare, propagated in the late 19th and early 20th centuries by either well-meaning, but ill-informed doctors or by outright quacks and hustlers looking for a way to make a quick dollar by performing circumcisions while promoting mental health and purity and a whole lot of other nonsense to concerned and easily duped parents. Then add the 2 world wars of the 20th century and other smaller conflicts which gave rise to universal military service and in the US, the desire by military doctors to standardize health treatments and prevention (against venereal diseases and infections), and you have the perfect cultural setting for circumcision to become the standard norm.
There is also the claim that circumcision sets those cut apart from others, makes them exceptional in some way, exceptional meaning better or initiated into something of a higher order. This explanation certainly works when circumcision is performed for religious reasons. It is connected with notions of purity, cleanliness, being part of a special group.
There may be a civil corollary to this way of thinking for the US. Many Americans so like to propagate the idea of American Exceptionalism, as a political, historical and social notion. So that possibly assuming another aspect of exceptionalism of a sort - namely being circumcised - comes to be easily and readily accepted.
This isn't meant to be any kind of critique. In fact, in the heyday of the British Empire, high ranking people from amongst others, the East India Company performing service in the (soon to be) colonies, were required to be circumcised, as otherwise many native (Muslim) rulers refused to conduct business of any kind, trade or political, with uncut and therefore impure infidels. Circumcision therefore became amongst a certain (high) class of British to be considered a mark of distinction, as a prerequisite to being in the Service of the Crown abroad in an important manner.