The importance goes beyond the specific relevance to the energy sector. Guarantees like this one are precisely the agreements that enable smaller countries to subsist in peace, without having preemption or the defensive seizure of territory constantly on their minds. The point of these agreements is to be evidence of will and determination on the part of the great powers: the evidence that prevents wars.
The record of what happens when great powers abandon such agreements has been an awful one, over the last century. Besides lessons in passive aggression, the Obama administration should give them in irresponsibility too.