Decryption is done on user device so default iteration is set not to be too slow on slower devices. If your all devices are fast enough, It's good to configure it.
It's fine that you want extremely secure iteration counts like 99999999999999999999, but you should wait 9999 seconds to unlock. Every product should have just right default value. LastPass default iteration value was maybe fine in 2008 but computer power is improving.
