You are wrong that they cause no harm. Did you miss my last post about how it causes a very long pause every time Thunderbird updates, because it is searching for an update to the ESET plugin?
This causes no end of support calls to me whenever a Thunderbird update occurs.
But, no worries... I had opened a case with ESET, and they just replied, and as soon as I saw where they were going with how to remove it, I realized I could have done it all along with the policy editor (we are an enterprise customer and have the RAS/RAC for managing our clients).