Because Romo never had a really complete team, ie offense, defense, ST. Some could argue that Daks had had a more complete team, the offense is not as high powered but has a great RB, defense is slowly rounding in to form, it at least has good players at each level, ST is fine if bailey regains form.
Also with Romo, in my opinion no game was out of reach. Yes he could make ill advised throws but the majority of the games Dallas was losing in I never though they were really out of until the final gun. With Dak, I think if a team gets a 2 TD lead you can chalk it up as a loss.