For me it depends on the situation. If I have built a lot of cities along fresh water, then no, I will routinely ignore them. But, for example, in my current game I have almost no fresh water in my zone, so most cities are simply coastal. Once the majority of my cities have gotten their 2/3 districts up, I've been running them to get the extra housing, and I'd like to think it's helped (given all my cities are basically at the housing cap, and before I started invading everyone I was chock full of happiness everywhere, so could easily grow to fill them).
So I have found them useless when they first appear, because I often don't have the districts up enough yet. And they're useless at the end when your cities are developed. But I've found them useful in this case in the middle of the game.