It isn't doubling the refresh rate that makes it look sharper, it is turning off smooth motion at 60 Hz and using a tuned ~24/48/96/120 etc. Hz refresh rate that is sharper (60Hz without smooth motion would be just as sharp but would have terrible judder). Smooth motion blends frames to present the source frame rate as accurately as possible on the display's refresh rate. It does not smooth the motion beyond avoiding terrible judder but the use of blended frames does reduce apparent sharpness to some degree.
At high refresh rates this becomes minimal and the experiance of a tuned 23Hz and smooth motion at 120+ Hz is effectively identical.
Edit: I don't know what issues your TV has but I am confused by your rant. I don't think anyone has ever suggested 50 fps on 60 Hz. That looks bad no matter what. You really want the refresh rate to be at minimum over double the frame rate before smooth motion is a decent option.
Smooth motion for any normal frame rate on a 144 Hz screen works very very well. Motion blur is still exactly as the movie was shot, there is nothing that changed or should be changed about the motion blur when using smooth motion at any refresh rate. madVR's smooth motion is not like your TV's or whatever motion interpolation. We are talking about how often the electronics update, not how often the image actually changes.
I am also not saying matching the refresh rate is not ideal, or that using double the frame rate is better; only that it is not worse.