Today's consoles seem like repacked PCs with few changes but the older ones seem like actual dedicated gaming hardware, especially PS2 with Emotion Engine and PS1 as disk controller, what the hell (in a good way)?!
What I don't understand is why this was the case. I wonder if a general-purpose-PC-like architecture that was powerful enough to play games of the intended caliber was simply too expensive at the time.
Some games on PS2 like Fatal Frame or Haunting Grounds are impressive even by today standards and could pass for double A games nowdays (entire 17 years later). That's just impressive. And their hardware specs read like a real spec for a gaming machine (the EE's 2 VPUs, the PSX in PS2 for compatibility, etc.), not just "bunch of PC CPUs and GPUs from AMD in a box + blueray drive". Ironically, first original XBox prototype was actually (I think or maybe its a rumor) made out of laptop components.
NES was a bit weak in comparison but very cheap (Pegasus costed like 50 PLN in the early 2000s).
That wasn't because the designs were more clever, mind you; but just because the hardware designers didn't need to think in terms of an architecture that contained concepts like dynamic frequency scaling and multi-monitor support and a kernel that blocks on disk IO. Consoles were hard real-time embedded systems, and the games were their unikernels; well into the PS2 era, console game were still relying on VBlank interrupts for physics timing!
And what this got you, was effects that were only achievable on an $8000 SGI workstation, for $300. Slightly-beyond-state-of-the-art, for cheap. But in exchange, it forced heavy consolidation in the console manufacturer market, because developing that specialized hardware wasn't cheap (like it was back in the 8-bit micro era.)
But "generic" PC GPUs eventually started scaling in power geometrically, to the point where the specialization and hard real-time guarantees just weren't needed any more to achieve modern graphics cheaply. The low-level-targeted specialized-graphics-ASIC technique wouldn't be of much benefit today, because six months later there'd be another new "generic" GPU out that could do what that ASIC does without breaking a sweat.
The same thing happened in networking: ASIC switches with special RTOSes were needed to run data centers—until CPUs and PCIe advanced enough to take over. Now everything (except Internet-backbone gear) is Software-Defined Networking, i.e. generic boxen running VMWare EXS running a Linux/BSD router VM.