This wouldn't be a particularly bad idea, especially as Wheelspins appear to have a certain RNG that's geared to give you cars you don't already own; I own every car available in the base game, and have done since about four months after launch. As soon as the HW cars were added to the shuffle, the next three cars I won were the new additions. When they announced the Midnight Battles, I sold off the Murcielago for a profit, and lo and behold, the next car I won in a Wheelspin? Another Murcielago.
I mean, it could just be blind luck on my part (and IIRC VIP membership makes the wheelspins likely to give better prizes), but its a bit too much of a coincidence in my book. If this really is how it works, then adding the Playlist cars would easily placate the situation somewhat. Even if a certain player doesn't win them, them being more readily available would lower prices in the Auction House and drive down the frustration for a lot of people.
An alternative solution is to shuffle the rewards for the Midnight Battles every month or so and maybe do a community vote a la the Backstage in FH4 for the four cars people would want implemented.