The Keystone Pipeline will not be taking land or homes from the owners. TransCanada seeks a 50-foot-wide strip of land on which to build the pipeline. Landowners would continue to own the property; the pipeline would be constructed and operated below ground. It is an eminent domain request (which I understand Keystone has dropped) but for an easement, not a full outright confiscation of private property.
The pipeline will transport crude oil from not only the oil fields in Alberta Canada, but also from the oil fields in Montana, Nebraska and Oklahoma to refineries in Illinois and Texas. Drill Baby Drill! But drilling necessitates transporting that crude oil from the oil fields to the refineries.
Easements, even when they have to be done through eminent domain are sometimes a necessary evil. Otherwise (and I agree with you) we would not have oil or natural gas pipelines or high power transmission lines, highways, and while the concerns building and operating them may be private enterprises, one can make the case of it being for an overall overriding public good.
That is completely different IMO from evoking eminent domain to force property owners to sell, to have all of the property taken even at a FMV, their homes and or businesses torn down in order for a developer to build a shopping center or a limo stand or a sports stadium.
There is no reason for eminent domain to ever be used for a shopping center.