I'm an atheist who grew up singing hymns every day at school. For me, singing a hymn is not really an act of worship, it's just singing.
I'm quite wary of giving kids the idea that there's some kind of deep and meaningful or supernatural significance to singing words about God, so no one should do that unless they believe with a capital B.
I prefer the idea of gradual dilution and hymns becoming gradually seen as less religious, rather than removing hymns or anything with even a hint of religion or spirituality or ritual from schools.
I also wonder if community rituals like singing, and including a few hymns and songs with spiritual and ethical messages from a variety of sources, may actually inoculate people a bit against more extreme forms of religion, rather than making them more likely to fall into them. Not by making them hate spirituality but by just by providing the sort of minimal level of community ritual that's more than enough for most people.
Over the years I've come to the conclusion that religion isn't going anywhere, so possibly broad but very shallow participation in the most benign rituals from a variety of religions may end up being better for humanity than no religion for most and deep religious fervour from some.
So, for me it's not about prioritising hymns, it's just about not excluding them or trying for some kind of secular purity, because I don't think that will work, long term. I'd rather just treat them as songs that came from a religion, but anyone can sing them and enjoy the tunes, think about the ideas and so on, without that constituting some kind of declaration of belief. I think that would be a more positive thing for society long-term.