The impression is of familiarity, you do not feel small when you enter, very different from the cathedral that gives you the impression that you are small, here on the contrary it invites you to enter its ribbed vaults are low and we can appreciate its much better details
I guess the crypt works to have an welcoming feel due to the illusion of spaciousness that it can give. As you have stated, the vault seemingly not spacious for audience to heighten the spatial experience given by the detailing.
I personal find the crypt and the curves to be a refreshing element in any architecture. It shows fluidity not like the rigid and fine cut edges of modern aesthetics. Enjoy a slice of !PIZZA.