OP needs to value the opportunity of an hour saved in transit (the 30-min vs. 90-min connection) and earlier arrival time vs. the possibility of a missed 30-min connection (knowing that there are later flights same day from both DTW and MSP).

Yes, 30-min connections are possible at DTW. I wouldn't do 30-mins to the last flight of the day without being prepared to overnight. OP can check aircraft and see if the current schedule is mainline to mainline.

As for people who routinely book away from 30-minute connections, maybe they suffer the scars of inferior airports (MSP, DTW and ATL are all pretty good) and airlines that haven't been The On-Time Machine for decades.