Focused, the point of D-Nice’s settings is to get it as close to a certain standard as possible. This ISF standard is what moviemakers use as a point of reference and as such an ISF calibration is preferred to truly see the director’s intent when viewing a movie. The “filtered” look you referred to is two things. The D65K grayscale will yield a little bit more of a yellow-reddish look, especially when comparing it to Optimum. I find the Optimum mode to be just the opposite, not so optimum. Grayscale is too cool, colors are overly saturated, sharpness is too high, and black levels tend to be crushed.
The thing with a calibrated image is you need to set it and leave it for a few days to get used to it. It is proven that compared to the out of the box settings, a properly calibrated set will yield a more natural look, better shadow detail, truer colors, more detail and also be easier on the eyes, especially when watching in the dark. Focused, I would say, give it time. True, a properly calibrated image may still not be for you, but I still say give it time to see if you start noticing a difference.
You said it yourself, you have been conditioned to enjoy the brighter, punchier image.
Ultimately, you don’t have to use the settings, just use what looks good to you, since its your TV.