In the traditional physical therapy setting, I agree that it is usually a waist of time to use E-stim since insurance will only cover a specific amount of units/time per session, which are already too low to begin with (that is a whole different rant/topic to discuss). By using e-stim, you are taking time away from other, potentially more beneficial therapies to be utilized.
But IMO, EStim has it's place, but is commonly misused and over-used in replacement of other manual therapies and rehab. Thankfully I have worked in settings where I am not limited in the treatment by insurance companies. Even though I am much more of a manual therapist and rehab focused, so I don't commonly use E-Stim, I've seen positive results especially when trying to break the pain-spasm cycle when e-stim is used in conjunction with other therapies.