I can see a point to what you are saying. Dams can result in 1000s of deaths, but they already help millions to survive.

>>Are dams ever a good idea?

Yes, I guess, without dams the developed nations would not have been so developed either in terms of technology and even sociology. Without dams there won't be cities, without big cities there won't be mixing of different strata/groups of society.

So, when I think of dams I think of the immense value they provide to humans and their progress. It's difficult to get rid of dams. What we need is a lot better technology to ensure their reliability and robustness.

Another reason why we need dams more is: the sheer population increase is putting a hell lot of pressure on natural resources (including water, of course) these days as compared to 19th century. So we must address this issue also.

Also, the increasing consumerism should be restricted/reduced. The mindless consumerism is also adding to this pressure.