Yes, it's a preference just like anything else. Wanting Touch ID and/or preferring it on the front is also a preference. But we know what the general preference will be among the general population.
But again, as I mentioned price and specs aside. Most will choose the larger display in a smaller device footprint. Anyone would lose their money if they bet against that.
That's a separate conversation. Of course the new iPhone will be the most popular iPhone. But you had asked why anyone would choose the 8 Plus over the X, and there are very compelling reasons for that choice.