doesn't that mean that coins will be created faster than predicted though? If the blocks are allowed to be faster than 10 minutes but never slower then there isn't a counterbalance... so things could happen faster than predicted?
The opposite can, and has occurred. As the exchange rate decreases, unprofitable miners will remove machines from the network, and the blocks per hour will fall below 6. During the next re-target the difficulty will reduce to try and return to 6 blocks per hour.
Yes, if the hash rate continues to increase, blocks will be created faster than average and we will reach milestones sooner than expected.