Star Trek in many ways is a very 1950's way of looking at the future. We have big unified empires that take the place of Earth's nation states that are the primary movers of all events. We see atomic nuclear families that live in a PG-13 reality where nobody gets a tattoo (unless for cultural reasons), uses drugs or has sex Sex is only alluded too, it is almost never explicitly mentioned or even shown. It is a private thing that happens out of view of the audience].
The Federation officer is the epitome of the upper white middle class, civilized, educated, from humble beginnings and therefore still grounded enough to make meaningful decisions. And I think it is fair to say that the vision Roddenberry had for the future was shaped by the times, and that this vision is not what anyone realistically expects or would even want at this point.
Right now, our world is more complex, and we need more than the 'simple' answer that Star Trek in its previous iterations has provided. We are dealing not with the threat of nuclear war, but with small but bitter conflicts of ideology that lead not to "civilized warfare" but to terrorism and hate. We are moving to a multipolar world where in the old ideas of Good and Bad are fading, and instead we are presented with a palette of various hues of grays that represent our moral options in which we are damned if we do and damned if we don't.
Our universe is no longer dictated by huge immutable powers, but by many giant subtle ones: corporations, think tanks, NGO's, interest groups, each wanting to stake claim to a part of our lives. We are more connected than ever, but instead of unifying us this medium has splintered us into fanatic subcultures that are isolated from one another. Everything we hear and read is manipulated for a goal, presented and tailored in such a way to influence us to do something, to make us believe something or to buy some product. And the very infrastructure we rely on for governance, for economic growth, for peace and happiness is now one that is so large that we no longer know how to control it and we no longer trust it. The problems caused by it (global warming, overpopulation, income inequality etc) seem therefore impossible to fix. To put it simply: we have lost faith. Faith in our leaders, faith in our fellow man, and therefore faith in the future.
Star Trek as we know it does not have an answer for that. You cannot simply say: "Everything will be alright", we are past that innocence. But perhaps I should say, it only has part of the answer for that. Because in the end, the basic building block of any society, is always the individual. The choices you and I make and the reasons we employ for those choices matter immensely. Morality is part of the answer. At the same time however, the (currently) modern individual has to make those choices in a very different world than the one that Star Trek was conceived in and it will be difficult to find relevance for Star Trek if there is not enough connection to our current reality.