What does the ps3 slim have to do with anything, it wasn't more powerful than a normal ps3. I have no issue with slim models or cheaper alternatives, becuase they are generally targeting people who may not be able to afford the full priced version. These pro consoles for the most part are targeting people who already own the console.
It had a bigger hard drive, was cheaper, etc. IT's a basic idea that technology advances. Same with the DS. Same with phones. You know what you're buying when you buy it, understanding that there will be upgrades and alterations and improvements on later models. that's just how technology and time works.
Nobody buys a car and complains to the manufacturer that they got screwed when next year's model comes out. That'd be stupid.
My Console Library:
PS5, Switch, XSX
PS4, PS3, PS2, PS1, WiiU, Wii, GCN, N64 SNES, XBO, 360
3DS, DS, GBA, Vita, PSP, Android