It all depends how you look at the awards. In terms of popularity or sales or quality everyone is going to have there own opinions. There are also many GOTY awards that get given out at different outlets. Weather you take The Game Awards, Gamespots, IGNs or the 200 others seriously.
The point here is that Forza has been left unchallenged through-out this entire generation and even when it had competition it basically didn't matter because it over came the challenges and basically took the racing genre on themselves. If you are a racing fan than this will peak there interests more than the other awards. Different taste for different people I suppose. I am a huge Blizzard fan yet I didn't care about OverWatch winning GOTY because OverWatch just isn't for me, instead I found other games that year I loved more.
You are probably right, maybe Sony don't care as much as they use to in the racing genre, probably the same way they don't care about the FPS genre either as GG moved away from Killzone. I feel Sony has found there strength in the 3rd person action games. Its something they do really well in, much like how Xbox do really well in the FPS and Racing market and Nintendo in the Platforming market etc. Each company has there strengths which is good for the industry.
Of course everyone has their own opinions. No different than any other awards show for stuff like movies and music. But, at the end of the day, individual opinions isn't what people are going to remember. That's why they do the VGAs in the first place. It matters.
I'm just saying that Sony isn't worried about a 'battle' with Forza when they're moving onto new horizons and have benefitted as a result. Losing an award in a genre you didn't participate in is hardly something to fret over.