A lot of people want to debate that WoD was the worst expansion. The only flaw with WoD was the lack of content. The zones, music, raid design, pvp design, questing experience, garrisons, were all of high quality. I wish for a day maybe like wod classic or a wod remix where all the cut content comes back in that event then makes its way into retail.
But truly Shadowlands was the worst for a massive amount of reasons as listed by OP.