My understadning of lead is that it's pretty stable in pipes because they develop a protective coating of residue that prevents the lead from leaching into the water.

Problems only arise when the chemical composition of the water changes and that protective layer is dissolved and raw lead pipe is exposed. Also, at the residential or building level some types of construction can cause lead to continuously leech when the water sits. But that's easy enough to overcome by letting the water run for a minute or two.

I'm not saying to no remove the lead pipes but I think it's also a manageable problem if it's treated properly. The situation in Flint was 100% avoidable.