To me this is actually one of the attractive aspects of Wireguard compared to some other VPNs, it doesn't try to manage everything within the tool and delegates to the host's normal routing mechanisms. However it still by default conflates AllowedIPs and the routing table -- you can actually separate them (Table=off with wg-quick) and then manually add routes.

I agree completely with the sentiment, though I never actually mess with the routing tables.