Currently it is very hard for people to race others, in the limited 8 player, always online world. Most often, these people don't want to 'Randomly' race opponents. Bring back a multiplayer lobby and a Blacklist (world, nation, local, a la Most Wanted 2005) and this should solve the problem. Fans want to duke it out with others quickly and have a competitive incentive to see who's the best (the best of 8 players that always changes is hardly an incentive). Multiplayer lobbies has worked for you before, it works for COD, Halo, Battlefield, and many other highly successful games. This open world only scheme has been used twice (Rivals, NFS), it's not working. I know you guys are trying to revolutionize the racing game genre, but this isn't it, it's isolating the players instead. Where is the incentive for fans to continue playing after beating the story when they have to hunt down players just to get a race declined? Most don't have NFS friends to duke it out every night, as a litmus test, try having fun with others WITHOUT your dev team or friends. The fans are pleading for change.
This lobby option/menu doesn't necessarily have to take you out of the open world. Have it where you can view/select the race you want through the map, or have additional functionality when you arrive at a race marker. You could even have it as an additional tile when you click on the Pad on the PS4 controller, much like the Crew/Party tile.