This isn't the Middle Ages. The SSPX is not "medieval", and the Catholics who lived after the Renaissance and before Vatican II are not "medieval."
Maybe the werent, but they should have been.
If you take "medieval" to just mean a certain abitrary periodization of history, obviously not.
But if you take it as a set of foundational philosophical principles and psychological outlooks that were the reason that era was defined as medieval in the first place (ie, they were the cause of the Age and not the other way around)...then Catholicism is inherently medieval, and I certainly consider myself to be.
Medieval is a mindset, a culture, an organic and holistic set of attitudes. It is an all encompassing paradigm, and inasmuch as we can recapture it, it is the one we should have, as it is by definition the one formed by the full blossoming of the Church and Christianity into all spheres of life, public and private. There were many external things only accidental to it, but at it's core it is identical with the Faith.