No offense but the two defenses aren't comparable at all in how they were built, etc. And to think that this defense is simply teamwork and cohesion away from being a dominant D like those 90 defenses were is a bit of a stretch.
Dallas had more #1 picks on that defense than this one did. They invested more high picks in defense than this one has. Russell Maryland, Robert Jones, Kevin Smith, etc. Throw in Darren Woodson as a 2nd round pick. So was Ken Norton Jr. So was Dixon Edwards. That defense went after more high profile players (in trades) than this one has. Haley was a premier player when we acquired him. Tony Casillas? Don't forget he was a former first round pick of the Falcons and was very, very good for them. He still is the leading tackler amongst all Falcon DL in history.
Dallas also added Thomas Everett in 2012, who was a very good safety in the NFL at that time. He got into a contract squabble with the Steelers and Dallas made a trade for him. In later years, they went out and landed Deion Sanders.
There is really no comparison between the talent and assets invested in those 90s defenses and this one.
However, you aren't acknowledging all the players brought in by Jimmy Johnson and Co. that didn't contribute and were cut. Again, a 3rd round or 4th round defensive player that didn't pan out every single season. Sometimes both picks.
You didn't mention all the trades and veteran acquisitions that didn't work out in the 90's. Those guys didn't bat 1.000 when it came to getting talent, not by any means.
And this current team has drafted for defensive help high in every draft.
Five of the last six 2nd round picks were defensive players.
They drafted a defensive player 6th overall in 2012. Their first 4 picks that year were defensive players.
2014, all but two players were defensive players.
2015 their first two players and five of their first six were defensive players.
2016, three of their first four players, defensive players. And you could make an argument that the selection of Zeke Elliot had positive ramifications for the defense.
The defense has not been ignored, nor has it been ignored in free agency.
Hardy, although he didn't pan out. McClain was drafted #8 overall.
If the Cowboy went out and signed old veterans for big money they wouldn't have enough to keep their own young Pro Bowlers.
Again, the Cowboy defense in the 90's weren't good until they were good, that's when all the players began to mesh. It will happen to this current group, it will happen this season, not at first, but they will be much improved.
This is going to be a season to remember, in about three months we'll look back enjoy many of the posts you, me and everybody else put on this forum.