It is also a marketing stunt. India's space program is one of the most cost effective in the world. By going all the way to Mars in its first shot, it demonstrates that its low cost program is also failure proof, successful and viable. ISRO, the organisation that is executing the Mars program, hopes to secure additional commercial satellite launching business by demonstrating the success of its Moon and Mars programs.
Is NASA also a commercial entity, or is it entirely government funded? Can an African country walk up to NASA and have its own satellite launched at a fees? Just curious. ISRO is, and I guess that by getting more and more commercial business, it wants to reduce its dependence on government funding (and therefore political meddling). As we've seen in the case of the NASA budget cuts recently, living entirely on government dole doesn't always work in your favour.
Or yeah, maybe that too. If you're running a space program in a poor country where a number of other programs vie for the same budget, then demonstrating science that captivates the minds of the populace sure would be important. That way when the budget discussion comes up, ISRO can say that the people want science too!