NetworkManager-openvpn always adds default route without asking

In our university, we use a connection profile that gets several routes pushed from the server. However, no default route is among them. Still, when importing the profile into NetworkManager, a default route gets added with a lower metric than the previous default route.

I know that there is an option in the IPv4-settings to prohibit this. But why is this an opt-out? When the entire traffic should be routed through the VPN, both the server and the client config can use the redirect-gateway-option for it. If this option is not present, why does NetworkManager assume it should send all the client traffic to the VPN? This causes a) unnecessary strain on the VPN network if this is not wanted by the organisation, or b) the client's internet connection to fail when the VPN server does not forward connections into the global internet (which happened in my case).

I think, NetworkManager-openvpn should follow the behavior of the OpenVPN-client, which is forwarding traffic when redirect-gateway is either used in the client config or the server, otherwise not. Shouldn't it?