The devious reason is because Google wants to encourage you to use their services, which will in turn improve their services and enable Google to provide more value to Android users.
The more mundane reason is because it's a better location service than your phone's GPS. It's a fair question how much more privacy-preserving your phone is when you disable Google's Location Service, given everything else your phone is doing but let's put the privacy angle aside.
Phone GPS is not consistently accurate, even outdoors. By allowing Google to use other signals, such as nearby wifi, cell towers, etc Google can provide a more consistent and accurate location for your device while also using less power.
Otherwise, answer hit "no". But I think it's worth questioning whether it's so frustrating when Google Maps assumes it can use Google Location Services.