Still selling brand new machines with 5400 rpm HDs. In 2019. It undermines the brand. Any Mac a customer buys should have good enough performance. 5400 spinning disk hasn’t been fast enough for a decade.
It’s a fusion drive so most “normal people” likely won’t notice unless they have a huge photo library. My guess is they want 1TB so they can upsell you to 3 or 4TB, which would be prohibitively expensive with SSDs right now. Edit: I was wrong, the lowest tier iMacs actually have a 1TB regular drive. That’s crazy considering the lowest tier Mac is almost always the most popular.
Because 90% don't need computing power; they just browse Facebook and Spotify.
The Fusion Drive is available for $100 more, if you actually need to access local storage.