The scale of its success took everyone, not least Bowie, by surprise.
Just because he seemed to be surprised doesn't mean that he really war or that that wasn't his intention. Do you think he would've come out and told the world that he just wanted to be ultrapopular and make a load of money no matter how uninventive his music would become?
In reply to:
Anyone who thinks Tonight was a calculated attempt to woo the mainstream more obviously doesn't remember much about the mainstream circa 1984.