Q: Why don't we use the bells during Mass any more?
A: Bells were used to call people to church especially when they didn't have clocks. As church buildings got bigger and large pillars were built, especially in Europe, as many as two-thirds of the congregation couldn't see the altar nor hear the priest, who spoke in Latin. There were no microphones, so bells were rung to advise the people that something important was happening at that part of the Mass. Now churches are built where people can see the altar, where the priest faces the people, speaks in the vernacular and is heard more easily through a sound system. Thus the need for bells is no longer a necessity.
Furthermore, magicians use music and other distractions to highlight their magic. The Eucharist is not magic but miraculous. So that we may concentrate on the words and miracle of consecration, the possible distraction of bells is more often left out, lest the wonder of the Eucharist be confused with magic.