This idea has been explored by the "up and down" mod and the "starminer" mod. Despite being done, it isn't done in the way I'd like, and I'd like them modified, or simply recreated, as to allow for you to walk on any block, discluding air, liquids, and others with no collision boxes, without the usage of gravity plates.
Furthermore, if you use either of those 2 as a base, they both have critical flaws that should be fairly simple to fix.
Starminer. The gravity plates on this mod will change your gravity if you if you're 1 block near them, rather than touching them. As a consequence, if you're anywhere near a corner with them, it'll continually get you into a hellcycle until you clip through the wall. This trait will also allow you to turn corners larger than 180 degrees, but seeing as the falling speed accelerates you so fast, it will send you careening towards the endless abyss at the speed of light. Also, the camera makes you want to vomit.
Up and down. The gravity plates here fixed all of the previous problems, but with a huge deficit. You can not turn corners greater than that of 180 degrees. Seeing as I want this integrated into solid blocks without the usage of plates, it could potentially be modified to detect an adjacent side of the block you're on, without having to touch it.
All in all, there needs to be a way to turn corners consistently, without falling off. Playing this with the Cubic Chunks mod would completely change the way one would play the game.
I have commented this on This, and This forum post. Check to see if someone else has taken up the project before doing it yourself.