I've recently gone back and looked at Romo's first couple of seasons as a starter and I truly believe we could have accomplished something if Romo had been as seasoned as he is now.
He's always had it, but there are things he understands about playing the position now that he simply did not as a young quarterback and it's easy to see the difference. The 2007 and 2014 seasons remain the best shots we've had with Romo of getting to a Super Bowl ... and I think the 2014 Romo would have pushed that 2007 team over the top despite the mistakes many others made against the Giants. (He almost did it anyway.)
The difference in the 2007 and 2014 seasons is we actually had a pretty good defense in 2007 while the offensive line was good, but let us down in the second half against the Giants. If Romo had been seasoned, I think there are a few plays that would have been handled differently and that would have made a difference.
That's not excusing the Cowboys for not building a good enough team around him to be true contenders more than twice in his 10 years as a starter, but I do believe the results would have been different. For that matter, if he had been a seasoned starter in Parcells' last year, the Seattle game probably would have been handled differently from a coaching standpoint and no telling what would have happened from there.
I know you can't play what-if, but I certainly hate that the stars haven't aligned because of both bad fortune and bad decisions during Romo's career. Feel the same about Witten. I'm glad that DeMarcus Ware at least has a ring to go with his stellar career, even if he didn't get it with us.