Because that's how IT thinks it should be right now. FQDN is always better than just local top-level domains. FQDN allows you to use Let's Encrypt (or true TLS), for example.
Call me old school, but I always access my router using the IP rather than the domain. Or I would use the GLDDNS address in combination with Let's Encrypt (see How-To: Let's Encrypt on GLDDNS domain )
But yeah, you've got a point here. @bruce maybe something R&D should think about? A quick fix might be to set the router's default IP (at least the usual 192.168.8.1) as a DNS entry on the public DNS for console.gl-inet.com? Or perhaps introducing mDNS via Avahi for "gl-router.local" or something like that?