Let me come at your question in a different way. In a mass, the non-gospel readings may be done by a layperson, but my comments would apply to both laypeople and clergy (bishop, priest or deacon). To proclaim the Word of God, you not only speak clearly, slowly and loudly enough for everyone to hear, but you also convey the meaning and significance of the reading. How you do so depends on the reading, of course, but a lector who has prepared properly – who has read and reflected on the reading, taken note of the most significant words and phrases and determines how to give them emphasis, etc. – can breathe life into the text. If the text conveys anger, sadness, joy, or other emotions, they convey that emotion (without turning the reading into a performance). Better yet, if the lector is utterly convinced that God’s Word is true and life-giving, that comes through in the reading, too. You can tell if the lector is merely proficient but doesn’t believe or truly care about what he or she is saying. You can also tell when the lector realizes that God meets us in the proclamation of the Word and can change us.
I have seen a church fall silent and every eye fixed on the lector as God speaks to them through the scripture as proclaimed by a well-trained, intelligent and Spirit-filled lector. The bible is not just a book. It is God’s living word, food for the soul, a light that illuminates, a sword that judges. Bringing God’s Word to life is much, much more than mere reading.