Why is there no DHCP Lease settings on a $200+ top tear router?

Having more control is usually a good thing but the reasons given so far for the ability to change the lease time don't look very compelling.

A really long lease time of 10 days is potentially going to cause DHCP address pool exhaustion in an environment where a lot of unique devices come and go.  Think guests with smartphones.  Maybe OP's environment(s) don't have this risk but it still seems ill-advised to increase the lease time for all devices for the sake of a printer.

The lease is still going to be lost on the 11th day.  The printer that was shut off for 4 weeks is still hosed.

The lease is going to be lost whenever the router is rebooted.

Netgear routers have a limit of 32 clients per Wi-Fi band.  Too many long-lived leases may result in hitting this limit.

A static IP address or DHCP address reservation is a much better solution than globally increasing the lease time for all devices.  It's a point solution to a point problem.  Also, I'm skeptical of the argument that 99% of the people don't know how to use them.  By this same argument, people won't know how to set a DHCP lease time.

Finally, people really should not be accessing printers by a fixed IP address.  Network printers almost universally support Windows Printer Sharing and are, therefore, accessible by name.  Many also are reachable through their mDNS (called Bonjour by Apple) name.   Windows, OSX, iOS, Android and Linux can access printers by their Windows name.