What is the rationale for using cryovials instead of regular, sterile centrifuge tubes for the storage of mammalian cells?
With a good aseptic technique and without touching the cap directly, there should not be a significant risk of contamination in regular microcentrifuge tubes. Is the plastic quality fundamentally different (in terms of leaching chemicals etc)? Both kinds of tubes are usually made of polypropylene so it's not obvious how they would otherwise differ.
There may be a difference when storing things in direct contact with liquid nitrogen (as regular tubes may leak), but many cells can be stored for years in a -80°C freezer, a temperature at which most molecular biology tubes are perfectly stable.