Thanks to everyone who has posted so far. Some of these ideas were exactly what I was looking for when starting the thread. I appreciate the reasoned thoughts of everyone on both sides of the issue.
It seems to me, more "rules" attempting to level the playing field would reduce the quality of football, but would increase parity (that's if the "rules" were even effective in what they tried to accomplish).
In a sense, the purple powers aren't alone in creating the disparity. The "gap" in D3 football is also widened by schools who are given a wide open opportunity and choose a comparatively minimal level of commitment to the football program. I'm not saying this is bad, because as someone noted, the university is not an NFL franchise and has far broader goals. However, when schools choose to keep status-quo as opposed to growing/strengthening their program, it may actually be a sign of a healthy "system" (D3 football) for them to fall further behind others with a stronger commitment.
And certainly whatever schools choose a comparatively minimal commitment to football (again, not inherently a "bad thing"), really have no business aspiring to a national championship anyway. D3 football is still made up of highly competitive athletes and coaches. It is legitimate, competitive college football. I think any effort to "level the playing field" by somehow restricting the commitment levels in some ways would serve to de-legitmize D3 in people's eyes, not increase interest. (I realize no one has really advocated any rules changes to level the playing field, but rather noted their belief that the field is not level).