People are forgetting that we did not attempt to play out from the back at all against Brighton, which would have suited Maguire just perfectly. If we are going to play like that (e.g against Tottenham, or in the cup final), Maguire will be fine. I think people also are overlooking how lucky we were not to concede from any of the headers Brighton had, pretty much free on goal and with no one challenging for the ball. Maguire could have contributed in this regard. Some better finishing from the Brighton players is all that would have been needed to lose this match, and the storyline of how well we defended would have been very different.
Shaw and Lindelöf did well - don't get me wrong - and if the tactics are to play out from the back, they are my preferred paring as well. If not, we can just as well play Maguire and rather capitalise on Shaw's crossers into the box.