The Amex Delta Platinum card definitely comes with its perks and advantages, especially if you're likely to spend at least $25,000 (in total) on it in a given year. The Delta Amex is not to be confused with the classic unbranded Amex Platinum card (with the Roman Soldier logo); the classic Amex Platinum is very similar to the Amex Delta Reserve card.

Each GRR-MSP round-trip is worth 1000 Medallion miles (MQM) and roughly $250 Medallion dollars (MQD). That's 2000-3000 MQM and $500-$750 MQD per month. Assuming each semester is 4 months long, to make the math easier, that is 8000-12000 MQM and $2000-$3000 MQD per semester. Two semesters per year at that rate would be sufficient to qualify you for Silver Medallion status. Silver Medallion (abbreviated "FO" for historical reasons) gives you a few perks -- the biggest one to me being the ability to choose most exit row seats for free, since I'm 6'-3". If you don't fly as frequently as you envision, having the Amex Delta Platinum card could help supplement your mileage and dollar requirements and still qualify for FO status, IF you spend $25,000 or more annually on Amex. The Amex Delta Platinum card comes with a $250 annual fee, BTW.

If you're going to be flying that often AND you're likely to spend $25,000 or more annually on Amex, I do think the the Amex Delta Platinum card will serve you well. If you aren't likely to spend the $25,000, don't rule out the Amex Delta Platinum card but see if the Amex Delta Gold card makes more sense for you.