There sure are a list of specific Mission Objectives of the mission - you can read it on the ISRO's page for chandrayaan.
But i doubt you are asking about "objectives" as much as "purpose"
As replied earlier, ALL countries go through a gradual evolution in their space-faring technologies - and India is no exception. We HAVE to take small steps before we can leap.
Im sure you did not mean any ill-will but we tend to get carried away sometimes by sci-fi movie flicks about deep space exploration and the like.... Sure, they WILL happen, and sure India will do it too... we may just be a generation or two earlier.
You have to remember that a Moon mission - even an unmanned one – is a far cry from ISRO's beginnings in the 1960s, with a church in Kerala as their first office.
By the way, the Chandrayaan mission DOES have a few novelties which has not been tried by previous lunar missions.
1. A dedicated Radar - Miniature Synthetic Aperture Radar (MiniSAR) - would map the permanently shadowed "other" side of the moon. (most countries have limited their exploration to the earth-facing side of the moon)
2. The Chandrayaan-1 X-ray Spectrometer (C1XS) is essentially the newer and upgraded version of the SMART-I spectrometers used in ESA's recent moon missions
3. I also believe that the orbital plane of the moon-probe would be different from all other previous missions - chandrayaan plans to orbit the moon along its poles while all others usually orbit the moon in an equitorial plane
Essentially, Chandrayaan would provide much more comprehensive information - on the topography and metallurgy of the moon - than whats available to the WORLD's scientific community currently. Google is good alright, but not THAT good - to fetch info that we dont posess yet.
Regarding the social angle - whether we need to spend this much money on a moon-mission when we have a lot of poverty and social problems in the country - this needs a more detailed introspection....
"They asked the same question when we built our first satellite, Aryabhatta, in the '70s," notes Mylswamy Annadurai, Chandrayaan project director.
"ISRO has done fairly good work in using space for societal needs. Today we have satellites for education, crop, health and communications," Annadurai says. "Chandrayaan is today's equivalent of Aryabhatta."
but a simple answer would be 'yes, its worth it'.