Sure, it would be awesome and in useful, in many ways, to have a semi-permanent base on Mars. It probably should be a long term goal, but not a current focus.
Terraforming itself is unrealistic even as an extremely long term goal. Who knows what the technology will render possible, but Mars isn’t a great candidate for terraforming. Its gravitational field is weak and it has little or no magnetosphere to name a few things; both of these factors greatly degrade its capacity to maintain a substantial atmosphere. Even if Mars were a near perfect candidate, the cost, required will, and logistical/technological challenges would be staggering. We can barely make a positive dent in Earth’s biosphere (many would argue we've only had a negative impact despite the fact that our lives depend on it); and we only have vague ideas about how to begin building any kind of atmosphere on Mars, much less an atmosphere conducive to Earth-like biodiversity. An Earth-like atmosphere is just one facet...and so on. It would only be a realistic endeavor for a vastly more technologically advanced humanity, not to mention one that otherwise had its shit together.
I've always held we are more likely to visualize ourselves before we terraform another planet.