Static IP addressing inside the tunnel is still a major pain point for significant use-cases, e.g. company-wide VPN access for all employees. How do you do static addressing for 200+ people with their own devices?
These end users likely do not already have wireguard on their devices so as part of the software rollout you assign them an ip. A /24 gives you enough addresses for over 200 people and a /8 future proofs you for a much larger company size. You can also just spin up different wireguard networks for different departments or even think about using IPV6.
This is the same for any large rollout of technology really. There may be some hands on effort but nothing that couldn't be automated with a spreadsheet and a script.