The tag editing you do that gets rid of out-and-out bad, ambiguous or irrelevant* tags is generally pretty good. My snotty email and this post aren't about those circumstances at all.
* I suspect our definition of [ir]relevance is about to differ.
My biggest issue with your approach to "extraneous" tags is that it leaves a question with an extremely narrow profile.
For an example let's consider a fairly generic command-line question about scripting Apt. It might start with
command-line bash apt package-management but after you've visited only has
apt. You remove relevant tags that are extraneous because you consider them inferable from context.
I am somebody who often decides which questions to answer by their tags. If something has had tags that I find interesting stripped off it, there's an increased chance I'm just not going to see that.
And I'm not talking about theoretical issues here. In the past couple of weeks, due in large part to your editing, I missed questions that I would normally spot and attempt to answer. At the risk of sounding like a total blowhard, when you get between me and my questions, it's the site that suffers.
To reiterate the intro, this is far from representative of all your edits (most of which are great) but the reason you and I keep clashing over this is that you're actively and deliberately hurting the broader, popular tags. I'm trying to explain here that by doing that you're hurting the questions and the site.
And I'm fairly sure I could find an accepted answer on MSE that states the world is flat.