That is definitely odd, I got my ps4 for 200 bucks by waiting for a couple of years (it was during the 2017 black friday I believe) and it was the newer smaller model with a larger hard disc too. But I guess ps5 did have major shortages for a long while for the first couple of years so I guess they figured they could get away with it. And apparently now in China they're again running out of them due to Wukong selling like hotcakes, so I guess this is a response to what they expect to be a very high increase in demand.A world where consoles are more expensive to buy the longer you wait after launch is a world I don't want to live in.
Also, this is the first year where (most) of the good games coming out aren't also multiplatform with ps4 too, they're just on ps5, stuff like FFXVI or Rebirth or Stellar Blade and Wukong so they prolly figured that will also increase demand some for the folks who held on to their ps4s for all this time.
The turn based Jrpgs are an exception to this, even Metaphor will still be on ps4 too. Which honestly is not surprising at all to me, considering persona 5 was a ps3 game while looking as amazing as it did.