The Delta branded Platinum AMEX card does not give you lounge access (just a $25 per visit benefit), only the Delta Reserve AMEX (or the unbranded Platinum AMEX) provide free lounge access.
In your case, it doesn't sound like the card would be that useful. However, there are certainly Diamonds who can't meet the MQD requirement and/or who value the MQM boosts and for whom the card does make sense.
Last edited by xliioper; Dec 20, 2013 at 11:15 pm