To be fair, we have three NASCAR Toyotas from 2017, the year the game launched. And we've got the '93 T100 Baja Truck and the '92 AAR Eagle Mk III, so rally cars and older prototypes are at least present.
I'm grateful we got any Toyotas at all. Of course I would love more. We all would. That's why those "Is Toyota Coming Back To Forza?!" rumor videos are such effective click-bait on YouTube. None of us were privy to the negotiations between T10 and Toyota. And don't forget that T10 is a wholly owned division of Microsoft, so those were really negotiations between Microsoft and Toyota, two of the largest corporations in the world. We will probably never know what went down between them. We can guess that the Toyotas we do have were licensed through third parties thus giving T10 a loophole allowing them in the game. We don't know if there are more loophole Toyotas they could license. It's entirely possible there may be more and T10 is choosing not to license them so as to not piss off Toyota and keep them coming back to the negotiating table. We just don't know.
All we can do is live with what we've got, and hope the decision makers at Toyota comes to their senses and realize not being in the largest and most successful racing games in the world is not a good business decision. But if anyone at Toyota happens to be reading this, just think about this: if this goes on much longer, there will be an entire generation of kids who will be basing their IRL car buying decisions on the the cars they can fall in love with in their favorite racing games. Those kids will be racing Nissans, Hondas, and Mazdas. They won't be racing Toyotas.