It is in Google's interest
For app makers to lose access to the tracking info, but for Android itself to keep collecting it. That makes using Google's advertising services more attractive as they can be better targeted and further disadvantages Google's competitors like Facebook.
Well, ignoring all the data that suggests that personalized/targeted ads don't help beyond more "bulk" targeting techniques that advertised used long before computers - i.e. basing it on where you live, your age, your income range (which if nothing else can be generally inferred by where you live) and so forth.