As someone that's been involved in wildlife science relating to conservation and management since the mid-90s, I agree with Rob's last sentence. The speed of science affecting meaningful change is painfully slow, and the speed of human population growth/environmental degradation/management needs/changing political whims is significantly faster.
However, Rob's first premise, that we would have done something if only someone had suggested it, is totally naive. I can't think of a single modern wildlife conservation situation where some proactive protective policy took place based solely on the power of a suggestion or opinion with no science backing it up. Even after years and years of study, after which point an unknown might gradually become "common sense", there will be pushback from some sector of the general pubic that doesn't agree or doesn't care or doesn't want to pay for it, etc. Just look at the debacle around the Snake River dams. I can think of many other situations where there are known biology "common sense" solutions that could fix a wildlife conservation problem, but there are impassable social science or political roadblocks in the way.
This is obviously a simplification but in my experience, the population can be split into two groups:
Group one has the folks that care about coho salmon and is willing to foot their share of the bill to pay for the filters on every storm drain on every street in every town along the Puget Sound watershed. This group believes the solution to protecting a resource they care about is "common sense" and they are willing/able to handle the inconvenience to fund the solution. This is the minority group.
Group two is a much larger portion of the population that includes - but is not limited to - the folks that might not even know what a coho salmon is, let alone how their tires might be killing them, and they certainly aren't willing/able to pay more for greener tires or countless filters to protect a stupid fish.