It's a nice idea, but I don't buy it. What I like most about vim is how few unnecesary moves I make with my hands - in particular my wrists stay in the same place all the time; reaching for arrows would require moving the whole forearm, which I don't like and which breaks my flow.
Also I'm curious about this quote from OP:
I just might remap hjkl to split navigation,
because I use hjkl less and less, favoring
navigating in other ways. Sounds crazy, I know ;)