I heard that the UK released Buffy on widescreen season sets and they ended up having the exact same problems that you mentioned in your post.
Starting with season 4, yeah. When I watched Buffy on Netflix last year, it was the same; seasons 4-7 were streamed in the widescreen format. It was quite obvious just by watching that the show wasn't meant to be shown that way. Boom mikes, cameras, crew members. One instance that stuck with me was during Buffy's vision quest in "Intervention", when it was just supposed to be her and the First Slayer in the desert, and you see some guy there in the shot (No, not the Cheese Man; that was in "Restless"