Adding some 3D hardware doesn't inherently make a system anymore powerful, and certainly not for emulation.
The Playstation is the PC equivalent of a 33MHZ 486dx with 2MB of RAM.
While the Super Nes is the equivalent of a 4 mhz 286 processor with no math coprocessor and the superfx chip games added the equivalent of that coprocessor.
Both are capable of quite a bit, but neither is really suitable for emulation. A good programmer could probably emulate some of the slower, simpler titles (not to mention the ones with small rom sizes), on the playstation, but anything else would have to be ported.
The only reason PC games didn't just blow away console games back in the older days is because PC video hardware was far from standardized, and thus the programmers couldn't do much to take advantage of what WAS there.
It still isn't standardized, but now it is so powerful that it doesn't matter, which is why PC games will probably eternally remain far ahead of console games graphically.