Actually, the main reason for the haste is because of the fallout of a political corruption scam. One of the junior coalition partners upon which the govt is dependent for survival, was given control of the telecom ministry as a perk. They then promptly used their control over that ministry to set up a lucrative scam which would see satellite bandwidth sold off for next to nothing to a foreign interest. Actually, the foreign interest was a shell company set up on behalf of some American VIPs including former US SecState Madeleine Albright.
When news of the scam broke, the govt was in a panic, because it knew it couldn't prosecute its coalition partner without suffering a collapse of the govt, triggering fresh elections. They don't want to go for early elections at all costs, because they know they'd all lose badly. So they did the only thing they could - they put all the blame on the ISRO chief at the time of the scam, Dr G Madhavan Nair, for not exercising adequate oversight.
Well, Dr Nair protested very loudly, and was not a willing fall guy, and some senior colleagues even resigned in protest too. But the ruling politicians were determined to save their own necks at all costs, and blacklisted him from holding any govt positions, along with a few others. Dr Nair is most famous as the driving force behind India's Chandrayaan mission to the Moon, and of course is widely respected in Indian space circles and at ISRO.
The handling of the whole mess caused a lot of heartburn at ISRO, leaving a lot of people feeling demoralized. So the Prime Minister's Office has recently decided to throw up a Mars mission as a sop for ISRO's beleaguered scientists. That's why the whole Mars mission is going from conception to imminent launch in record time. When politicians worry about losing face, then money is quick to flow, and the normally lean-funded ISRO isn't going to turn it down.
Well, you know the old saying - "Found a horseshoe, so let's go buy a horse!"
Wag the dog, anyone?