From publisher blurb:
Bard dancing with lights circling around in the same tempo. Bard playing a harp with trees around swinging their branches to the music. …If bards have not been using these stylish ways to enhance their performance all along, then it's only because they had no idea of what good things some simple cantrips can do to their performance abilities.
The new option of combining cantrips and bardic performance presented here assumes that adding some magic flavor to performance can actually make a mechanical difference. Any such performance requires more time than the basic bardic one - after all, if you need only a free action to maintain the classic performance, then it should be considered effortless.
Along with extra time, cantrip performance usually requires greater skill, often calling for a Perform skill check to produce desired effects. This combination, as well as potential new bonuses from successful cantrip performances, makes them a meaningful game choice rather than same round-to-round routine.