Wearing a coating over your nails, whether it is nail polish or artificial nail enhancements, is not necessarily "bad" for your nails. Most of the artificial products today are hydrophylic, which simply means that they will allow a small portion of the natural nail moisture to transmit through the surface and evaporate.
Polish does not do this; however, any excess moisture that builds up in the nail plate will immediately evaporate when you use polish remover because of the acetone in the remover.