I agree with your general argument itcdbuck that a 40-time is pointed to without context.
One other factor I'd look at which I think is different from an studly O-line is the blocking scheme itself. Talk about being hard to parse aprt from the strength of the O-line itself, but there is a difference.
Just give you a couple of examples, with very different personnel.
Take the Broncos, they seem to be able to plug in any back and get 1,000+ yds out of that player. A lot of this must be attributed to the coordination exercised by the O-line. Much comes from the (controversial) nature of their blocking scheme as it promotes the use of chop blocking. Their O-line personnel are not cited as the biggest or strongest though they are clearly very effective.
For a heavyweight contrast, consider when Riggins was running behind the disciplined blocking of the Washington Redskin "Hogs" line. Huge line for its day, also very effective and well suited to a bruising back like JR.
I guess my point is that having the personnel on paper is one thing, getting them to execute in a coordinated scheme is where 1 to 3 yard gains turn into 4, 5 and more yards per carry.
Then I'd look at the extension of the run.
Again its tempting to fall back on the 40-yd dash time as the main metric. This tempting conclusion gives short thrift to the down-field blocking by the wide receivers. Classic case in point is the contribution made by Heinz Ward for the Steelers. Where a 40-yd dash time has highest value is surely in A -- getting to hole, or around end quickly, and B --uncontested open field running away from a secondary tackler with an angle on the play.
So with all that my "sort" on your list (plus additions) is
Great O-line
Blocking Scheme Execution (By Line and by Downfield Receivers)
Heart
Vision
Balance
40 time
tackle breaking ability/elusiveness