I do think the link road will be something of a game changer for DSA. It will make eg Sheffield close enough for friends and family to drop passengers off without it being a major hassle. Previously this wasn't the case.
If you live in central Sheffield you can conceivably leave your home 2 hrs before your flight is due to leave and arrive at the airport with 90 mins to spare. Even allowing for traffic you should still be safe. You can't do that if you are flying from EMA, LBA or MAN.