Americans really love their signifiers of negative freedom ("freedom from") and negative identity, and they turn those into religions just as much as any religion they might actually practice. So the tradcath thing is partly a silly aesthetic pose (e.g. Dasha from Red Scare), but it also usually serves an actual need, even if it's something really neurotic. As the evangelical Protestants have become so perniciously anti-intellectual and backward, the tradcath option looks more appealing to those who value education and at least a minimal amount of intellectual content to their spirituality. It also has a big performative aspect (lots of costume dress-up for the clergy, Latin Mass zealotry, etc.) that allows one to differentiate from the evangelicals (negative identity). My guess is that's why you see so many high-profile converts lately among the power elite.