A 2019 iMac 21.5" 4K Core i3 base model is $1,299. 2021 iMac 24" 4.5K M1 base model is also $1,299.I think if you like a good screen, the 24” iMac is still quite a good buy. You just don’t get screens that good which are standalone for that price. And my computing needs are pretty minimal, I write and do a little photography these days.
Isn't it amazing that Apple was able to keep to price points even during a worldwide pandemic? I credit it to lowering materials used, lowering shipping weight & shipping dimension, simplifying manufacturing, optimizing supply chain and Apple's cash hoard.
TBH if the 27" 5K display had a M1 or even M2 I'd buy it. I'd expect it to cost $1799-1999.
If you are coming from any iMac a decade prior to that it would outperform it in terms of performance per watt and raw performance other than say a Core i9 or Xeon.