When I use a SNES emulator, I jump through hoops to make it look like it did when I was growing up, simulating a CRT television and the artifacts of composite video. Why would I want to take my SNES and try to make it look like an unmodified emulator? That's the exact opposite of what I want. These games were never meant to be hyper-sharp and pixelated. In fact, some games rely on composite artifacting to make certain effects work.
In fact, I want an upscaler that I can plug my SNES into that will simulate a CRT. When I emulate, I combine a CRT simulation filter (which gives me a simulation of CRT scanlines and subpixel geometry while simulating the curve of a CRT) with a composite video simulator (which simulates the artifacts of composite video), and the results is very pleasing, looking much like I remember things from back in the day. With a real SNES, I don't need the composite simulator, because I can just use the real SNES composite output, but having a hardware device that does the CRT simulation (perhaps doing the CRT simulation shaders on an FPGA?) would make it look much better on an LCD or projector.
I realize that you can get partway there by running the SNES signal through a scaler to get to 480p and then running it through a scanline generator, but that's not simulating the physical properties of a CRT (like how a bright scanline appears thicker than a thin one), you're only getting partway there.