It's not perfect law, but will these proposed changes to the Act result in better protection? Of course not.
There is a consensus among biologists that the Act has been successful to a significant extent. Barring cost consideration at any level does seem unreasonable, but cost consideration can lead to really perverse arguments; more dollars can be had by killing and harvesting and elephant that not, so therefore...etc.
The existence of other methods of conservation beyond this legislation doesn't make for a compelling argument to weaken it, nor does the fact that some people will prematurely harvest timber before endangered birds move in.