The names of angels, magical words and incantations, as well as drawings as additions to the Torah sections in the Mezzuzah received halachic legitimacy by high regarded rabbis. Certainly, strong protest was expressed regarding these developments. The chief opponent was the great Rambam. We can present Rambam's opinion in A Guide to the Perplexed on the culture of amulets in general, which is not connected in particular to the mitzvah of mezzuzah. The custom of touching and kissing the mezzuzah as well as the use of the name of Shaddai demonstrate the same tension between the conflicting points of view.
Some sources require touching the mezzuzah before going to sleep and upon getting up in the morning.
For example, Rabbi Abraham Gallanti, in the 18th century refers to a common custom from Safad. When one leaves home, he writes, that person should put their hand on the mezzuzah to remember the unity of G-d and His commandments. On the contrary, Rabbi Akiba Eiger, in the 19th century, in Pozna, Germany, claimed that this custom cannot be traced back to the Gemorrah and forbade it. In our times, we do not include with the selections from the Torah names of angels, stamps, or other verses as in the past. However, I believe that the struggle today regarding the character and spiritual course of the commandment of mezzuzah has not as yet been resolved.