We live in a democratic society. If you have a pipeline that is not approved by the vast majority of people who might be near it or be affected by it in some sort of way, it's probably not going to get built. There has to be some way of dealing with these sorts of issues that makes sense. Regulators themselves can't deal with every single issue that might come up with an affected party. They can deal with things very well when it comes to what the NEB has traditionally dealt with, when it comes to making sure that nearby environmental concerns are dealt with, such as the risk of a spill. What they can't deal with are things that affect all of us, like greenhouse gases.
The things that affect all of us as a society need to be dealt with by the people that we, as a society, elect to deal with the problem, and that's our parliamentarians at either the provincial or the federal level.