There is something about the mid-engine layout that makes styling difficult. Back in the early 1970s I owned a Porsche 914, as I mentioned here. Although I enjoyed driving it (aside from an unwilling gearshift lever), its styling was awkward.
The mid-engine location, behind the seating and usually in front of the rear axle-line, makes for poor space utilization. The 914 had no rear seat, not even a small behind-the-seat shelf for carrying grocery bags or other incidentals. The spare tire took up much of the front, though there was a small trunk space above it. At the rear, there was another small trunk space, but it also was where the top had to be stored when it was removed. A rear-engine car (think Porsche 911) usually has some behind-the-seat space, but no rear trunk, so its layout is little, if any, better. Front-mounted engines make for the best space utilization.
But if the capability of carrying things beside a driver and passenger is considered much less important than a car's handling characteristics, then a mid-engine layout makes some sense, though another price it pays is in the styling. The problem here is that a sort of dead-zone is created between the back edge of the doors and the rear axle line. Giugiaro dealt with this elegantly on his 914-based Tapiro that I wrote about here. Alfa's styling staff wasn't as successful with the 4C.
All my quibbles aside, many potential 4C buyers will be attracted more by its high-technology engineering and resulting performance than how the car looks.