You can count me as one of those folks. Well not "extensively" but I did ride a friend's bike with Shimano Di2 and felt... meh. I didn't find that it shifted any better than mechanical, but I didn't expect it to, since mechanical shifts perfectly. Sure it works, but it left me wondering, what actual problem is it solving? What exactly is it improving?
It requires batteries that must be replaced or charged, and is more complex with more failure modes, less reliable. I've had mechanical shifting fail me once (broke a cable) in a lifetime of cycling. And that includes riding in some severe conditions like La Ruta in Costa Rica and similar rides across jungles, deserts, mountains, mud, you name it.
Bottom line, there's nothing wrong with cable shifting. It works perfectly, it's low maintenance, proven under extreme conditions, and lasts pretty much forever. It's been dialed into perfection over decades of engineering optimization. It's also simple (related to why it's so reliable and durable), more easily user-serviceable, and (finally, perhaps least importantly) cheaper. I also like the purity of a bicycle that has no electronics or batteries.
To put it differently, I would not want electronic shifting even if it cost the same as mechanical. I certainly understand that others do like it... each to his own! I don't mean to rain on your parade, I liked your post and enjoy reading what others have to say about it.