A good, carefully placed 5.1 setup beats a similarly priced 7.1 setup of lesser speakers, to stay in budget. I also think the "need" for 7.1 becomes more and more sketchy for people with only one row of seating. It does however more evenly disperse the sound for a larger number of audience viewers when there are two or more rows of seats.
In A/V reproduction accuracy, there IS no concept of "accounting for personal taste/preference". As art consumers we don't "pick" the level of bass, nor the tint/brightness of a scene's sky, any more than we pick the ending of a novel or Mona Lisa's type of smile. "High fidelity" means "high truthfulness", faithful to the original artist's intent: an unmodified, neutral, accurate copy of the original master, ideally being exact and with no discernable alterations, aka "transparency".