I don't think it makes it look worse, but bummer you guys don't like it!
I think these kinds of art styles totally can benefit from these effects.
For example, look at this comparison.
It's from an older version of the SweetFx thing I was doing, but it totally still applies. In the original, the green platform up top just has a weird color shift that when blown up like this doesn't really make any sense. But, with the CRT effect applied, you can see how it blends together and actually looks like a rounded edge, rather than just some weird color shift.
Similar stuff happens with Shovel Knights horns. You get the idea of what it's supposed to be, but it doesn't really look representative of it. With the CRT effect, theres a slight color shift to make it actually look like a little shine on the horn.
In the previously posted example that you guys were responding too, I think another great example are the yellow blocks you can shovel spike on to break.
It looks like a mish mash when it's regularly blown up, but using the CRT effect you get that great transitioning between the layers. Looking back at these I do actually need to lower the brigtness down a little because the colors are getting a bit shifted here, but I don't think it can be plainly said "It makes it worse."
Also just throwing this one in too, but I think it does wonders on the King Knight's throne! The arm rests little indented curves actually look like they make sense, and Shovel Knights horns are actually rounded out and smooth like they're supposed to be.
Basically, the CRT effect helps colors transition appropriately, and it helps round things which are made of squares actually look like round things, instead of mooshed together squares.
Whether you like it or not, I think there's some merit to the idea that it actually works with the art style in a similar way that older games used the CRT bleed to create nice looking blends. I dig it, you don't gotta, but I think there's some real genuine benefit to it.