For the love of Gene, yes. In many cases, Star Trek is NOT about showing us a better future. Yes, they have eliminated unemployment, poverty and international wars on Earth (and, presumably, on the other Federation planets as well). However, they still have interstellar wars, and sexism (TOS' rule about no female captains), and racism (or rather, species-ism against rubber-mask aliens).
Well, be careful there - any series is a product of its time. TOS was showing a future better than the 60s. Not *the ultimate better society*, but something better than we had in the 1960s. That the society pictured wasn't perfect doesn't mean it isn't better.
The better future you're talking about is illustrated solely through throwaway comments about a setting and culture that we never actually see in real detail. The journey to how we get there is important, and yet it's glossed over in almost every Trek series.
Yes, we don't see details of how things work on Earth often, but detailed explicit depiction of a fictional culture is not the only (or arguably even usually the best) way to get that information across, especially in the weekly-episodic TV format, in which we get a whole whopping 40 minutes of screen time for a story that has to have a beginning, a middle, and an end. Even shows like Battlestar Galactica don't really give you much of the homeworld culture. BSG *eradicates* the homeworld culture at the start of the show, so you're working with a microcosm. Babylon 5, similarly, gives you a very localized view through mostly military personnel, rather than show you much of what Earth is like. You arguably get more of what the Centauri culture is really like than any other, and that's still limited.
TNG and TOS have a heavy dose of morality play in their structure. That the future is better is implied in how the main characters act towards those who are not part of their culture - "Let That Be Your Last Battlefield" is an example here. This is intentional, as it mirrors how much sci-fi short fiction handles such issues.
Trek has always had an issue of mixing species conflict with cultural conflict - issues with Romulans and Klingons are usually not stand-ins for real-world racism in TOS, so much as they are stand-ins for the Cold War. That they also happen to be on species lines confuses the issue, and isn't generally intentional. I'd argue that TOS (and, by extension, DS9) do show much of the process of making the culture a better place, through the Klingons, especially. In TOS, they are almost entirely antagonists. In TNG, we have an exemplar to show Klingon's are really people, and then over the course of TNG and DS9, we go through the arc of making old enemies into allies, slowly accepting them for what they are, and having that be more and more okay as tie passes.