Even when more confirmations are required, a shorter block time will make the process faster. Waiting six minutes instead of one hour for six confirmations is an advantage.
That's not how confirmation security works, and it's been pointed out before in this thread.
I've explained in this thread why shorter block times do not increase the likelihood of an attempted double spend attack being successful, with the caveat that they make >50% attacks slightly easier and attacks using rented hardware less costly.
If I've missed something in my previous post:
https://bitcointalk.org/index.php?topic=232297.msg2470639#msg2470639Please let me know.
*Edit, I guess one thing I haven't mentioned is that a shorter block-time block provides a smaller block reward and is therefore more expendable in an attack.
For example, if the block reward is 25 BTC for a 10 minute block, it would have to be reduced to 2.5 BTC for a 1 minute block. If you have 10% of the network hashrate, and were attempting to double spend transactions with 1 confirmation, you would have to give up 9 confirmations worth 225 BTC to successfully pull off an attack in the 10-minute blockchain, while you would only give up 22.5 BTC (9 X 2.5 BTC) in the 1-minute blockchain.
While this is all true, it's also true that the likelihood of an attacker successfully double spending a 10-confirmation transaction in a one-minute blockchain is much lower than an attacker successfully double spending a 1-confirmation transaction in a 10-minute blockchain, despite both putting the same amount of block reward at risk for the attacker and both taking the same amount of time.
Also, in many cases, people would be satisfied with much lower levels of security than that provided by one confirmation in a 10 minute blockchain, and could do with one or two confirmations in a 1-minute block-time chain.