Regardless of miles or money, are you really going to get $3K in benefits? Given the current mayhem, I doubt.
I have done exactly two MR in 20 years. In both cases Delta "paid" me to make the runs because the flights cost less than Delta pesos I received in return. In fact, the first actually saved me money because I needed to make changes to a SkyMiles ticket and it would have cost $$ to change (It was free for platinums).
At the end of day - do the math. Being diamond for the sake of being diamond plays into the Delta's marketing (err loyalty) program.