I think that's a good idea and that they are going to add different surface grips anyway, but I'm not sure.
I think that it would be a perfect idea to increase the game's versatility and posibilities by adding different grip area's. You could create tunnels with 100% grip (you can stand still on them while upside down) that go vertical. This allows the developers to create tracks that go straight up or straight down for some parts of the tracks, it has to be a low (not necessarily narrow) tunnel that has this type of floor on both sides, so that a player getting hit by a missile or mine won't fall down all the way and be punished much harder by a hit than anywhere else on the track as they will be able to stick to the other tunnel surface and continue after the hit
This also allows the developers to create complete ceiling/walls tracks where you spawn on a 100% grip track, then need to get enough speed to stick to the rest of the track. Every time you fall off due to a mistake or weapons fire you'll respawn on a 100% grip track.