These days, almost all potential vim users have been using the sensibly-arranged arrowkeys for years before they start using vim. Vim puts a second set of arrowkeys right under their fingers, but it has a different, awkward arrangement that makes no sense on a modern keyboard and conflicts with vim's mapping of the real arrowkeys. In vim, the middle finger sits on the DOWN key and reaches up to go up if you are on the arrowkeys (as everyone assumes), but if you are on the home row, your middle finger now means UP instead of DOWN and to get DOWN you go LEFT.
Yet you "don't get" why that might be a problem for people? Really? If it is what you claim, "the single biggest roadblock," then there is something important here, whether you get it or not.
You argue that if you rely on these awkward arrowkeys, "you're doing it wrong anyway." Does that mean they don't really matter? If not, then the using the most prime of the keyboard real estate for operations that "real programmers" don't have much use for would be an even worse design than I'm claiming. If they are important enough to dominate your right hand home row, and I think they are, then your argument is meaningless and they ought to be rearranged so that this no longer "the single biggest roadblock."
And this second reason is silly. Training your finger to reflexively move left instead of up to insert text to the left is going to be a challenge of the same magnitude as relearning arrowkey movement? You think so? People who have been using "copy" for years have to learn that copy in vim is called "yank" and the t,T commands mean, well, "till", and you have all sorts of ctrl-* and meta-* commands to somehow learn, but having to learn to use h instead of i would be such a hurdle that it's really a show stopper for fixing the arrowkeys? That's really your second strongest argument?
These aren't real arguments. Long-time vim users argue that one of the glories of vim is its marvelous customization, but if you customize the basic movement keys, it's supposedly a horror because, well, you then won't be able to use a non-customized vim. So, what's the customization for? It's for secondary things, not something so fundamental. Then you're told by someone else that, besides, if you are using the movement keys much, you're not using vim correctly. Which sounds like a claim that the movement keys just aren't fundamental. And if they're not, what's the problem with customizing them.... What a bunch of nonsense.
It's all a smokescreen for maintaining backward compatibility with a poor design that has spread, mostly in the heads of old programmers (the ultimate "legacy systems"), but also into some software. But for those willing to admit that backward compatibility is the only real argument, think of how much MORE legacy there is these days for the real arrowkeys in the minds of non-vim users and in software of all sorts.
I think vim should change its defaults. It probably would if it were a commercial product, but that won't happen, because defaults in vi/vim are by and for long-time users, not potential users. But it is, as claimed, customizable, and so are most systems (like zsh) that have a significant vi-mode. Systems that don't have a serious vi mode but just toss in a couple of shortcut keys, like j&k, can be learned ad hoc, the way we have to learn all the other shortcut keys that have different meanings in every program.
So, I'm customizing vim & zsh, using the real (physical) arrowkeys occasionally if connecting to a plain-vanilla vim/bash, and it's working out just fine.