It would appear that the homily as a lesson on the scriptural readings given during the liturgy is not new, but a restoration of something old. (Is the restoration of this 'ancient' ideal of the homily actually given in the documents of Vatican II? I think it might be, but I'll have to check.) It may seem new to some since the Council of Trent (iirc) gave a set (cycle, actually) of topics to priests to preach on, and the link between the lesson and the scriptural reading could be very tenuous. Still, there is something to be said for the Tridentine practice today, when the laity is so poorly catechized. Does having a three-year cycle of readings make it even more difficult to combine the homily with a systematic presentation of lessons?