A few years after release, physical copies of games are usually cheaper—often much cheaper—than what's available digitally. I picked up a new copy of Horizon Zero Dawn for $12 a couple of years ago. I got Uncharted 4 for $20, also new. I don't remember what the equivalent digital prices were, but I'm pretty sure they were closer to $40.
I honestly think it's a bit of a shame—and a problem—that game prices fall so quickly. It puts too much emphasis on the first few months of sales (even more-so than other media), and in turn forces companies to churn out new franchise entries that don't actually do anything new. But as long as this is the state of the world, I think you'd be crazy to get the model with no disc drive.