Let’s not confuse the question of antiquity versus novelty (the old as opposed to the new) with the basic question of quality and the related question of accessibility (is it any good and do we understand it?).
Assuming that we will sing hymns and not only psalms, every hymn (and every psalm, for that matter!) was new once. Many of the hymns we sing have been churned over time, and hopefully the cream has risen to the surface.
That doesn’t mean that every new hymn is worthless, or that every old hymn is good. Lots of our old hymns have been edited! We’re also not talking about accompaniment here, although it may be part of the package – that’s a question for another time! Let’s concentrate now on the substance.