Nonsense.
You think there is no better finish place? I only watched the last 20km or so, but they were riding on flat, wide roads then. (Also, I know Spain a bit, and my, there are enough flat wide, endless roads...) Only when the finish neared the roads were getting dangerous, because they were getting close to the city center. So, is the solution to let the races finish outside the city centers if inside or closer there is no straight wide road anymore? Yes. Simply, yes.
If the cities then aren't willing to pay anymore and the race cannot be held, fine, then it cannot be held. If cycling can only be financed when the health of the riders is willfully ignored, then it has no future. I suspect, though, there are solutions, but people are too lazy or greedy to find them.