"VIP" status for Forza Horizon 4 (and, presumably, other Forza Horizon games) basically just gives you a bunch of extra stuff, including more credits every time you finish a race. A benign example of the rich getting richer, through spending a little extra money on a videogame. It's nice to have I suppose, and it's not pay-to-win, therefore it is acceptable.
This was available for purchase individually, but it made no sense to do so as it was included with all the other DLC in the Ultimate Edition. Forza Horizon 4 isn't generally the kind of game where you absolutely must have a certain car, but the DLC was/is nice to have.