The interior is deliberately minimal and low-rent, just like (to a slightly lesser extent) an MC Stradale. It's not Alfa being tight, it's all in the name of saving weight. Bare carbon fibre is everywhere.
The seats are comfortable, which is really all that matters as when you are driving a performance car you aren't spending an awful lot of time looking around the interior.
Anyway, don't be fooled by the 4C, it's for the most part a track car that just happens to look like something that would be nice to cruise in on a summer's day.