If the exact location is important geoip is not accurate enough anyway. Forwarding to regional sites automatically is just annoying when it doesn't work properly or someone is traveling abroad.
However, there's a lot of use cases that semi-accurate geo-locations make sense. The first of which is analytics. If I'm a marketing person at a SaaS company, I want to know where my customers physically are if possible for a variety of useful reasons.
Good quality estimates for location also help with security and compliance use cases as well. If a user logs in from a new country on the opposite of the world, you can flag that and take whatever action you want whether it's to block them, fire off an email to the person who owns the account or whatever.
What reasons? What makes you feel entitled to that information if not volunteered?
I hope you're factoring in error rates. Because right now Google, with its billions of dollars to spend on geolocation, tells me that my laptop is in Albuquerque, and my phone is in Los Angeles. Neither are within 500 miles of either.
Of course, you can just get around this with a VPN.
There are many many cases where it’s relevant. Others have mentioned prepopulating or ease of use aspects. But you’re making big assumptions that the client has an interactive user at all. It’s important where you don’t own the client or there is defined behavior, say at a protocol behavior, that must be respected. Moving earlier than that there are cases where you need to route traffic before any sort of connection is even established.
I suspect you’re also underestimating geolocation precision and accuracy. Free datasets will get you the right state or city say 90-95% of the time. Cheap datasets get you to the right town or post code 95-97% of the time. Expensive or bespoke multi source datasets will get you reasonable post code, neighborhood, or even household & address accuracy. Think of cross correlating order histories per physical address, device fingerprints, and IP addresses/triangulation.