The faster blocks make sense though if you want to protect yourself from Earth miners (see discussion in their forum under "Evil Earth Miner Scenario".
Except it does nothing to protect you...Earth just needs more hashrate, and their blockchain trumps Mars', no matter how delayed.
It will make it harder as it adds a much higher burden on a co-ordinated attack from Earth. Yes, they will have more hashing power, but to advance such a large blockchain in such a short time frame it will need a concerted effort from Earth to do that. On top of that, if the Marscoin network adds a timestamping or other security measures that are local to Mars an attack from Earth is impossible due to the distance.
The retargeting is similar to 540 block coins, like Terracoin.
Imitating a scamcoin which has had problems as a direct result of the change, is not the best idea 
Regarding the coin supply: it aligns with the departure of the Marscoin blockchain to Mars:
Why is this a good thing? I'd think it make more sense to have most of the coins mined on Mars itself, not most on Earth...Depends. The idea is to raise the money NOW to actually help make the Mars mission a reality. Thus you increase the incentive for people to get into the currency before the blockchain leaves. Once on Mars, the Marscolonists have better things to do than to put their servers on a mining armsrace - Marscoin on Mars will then mainly become a transaction network. If need be, the minimal mining that will continue could be monopolized by MarsOne or whoever runs the base to pay early Mars settlers to incentivise the growth of the colony.
Appreciate your thoughts and input!!