I totally understand the idea of getting a championship, partially by sacrificing future opportunity, especially if it's been such a long time.
However, how long do you want that great feeling to last? How long do you want to feel good about your team's success? The natural reaction would be the idea of repeating. When your team is at the very top you want to ride success as long as you can. It's great to hear the respect/hate from the media and other fans and it's great to revisit that victory with fellow Cowboys fans or anyone for that matter.
However if a team goes "all in" it implies that they sacrificed future assets in order to apply them to a championship run. Your team is going to weaken significantly for some years.
Your only opportunity to truly celebrate that Super Bowl is the offseason leading up to the next year. That's all. There is going to be nothing to build on and there is going to be nothing to build with. Instead of remaining competitive for a significant period of time, it's over in a flash.
This makes a SB championship far less meaningful. The team took all the excitement of the future and threw it into one season and there is nothing to look forward to.
The Cowboys did go all in in 1995 by signing Sanders to a ridiculous contract. It is now 2024. Was it worth it? Prior to 1995, Cowboys fans went into the next seasons with realistic expectations of competing for another championship. These are the kind of teams that are remembered by all. They are the ones that win in clusters because they have a great team they can keep for several seasons.
History honors the teams that win championships in clusters, teams like the Cowboys in the 70's and 90's, the Steelers, the Chiefs, the Patriots, etc. A team might have a great year but the great teams have eras. They aren't built for a single opportunity. They are built to compete every season with a realistic opportunity to win it all. If they don't win it all there is next year.
If a team is built to be "all in" then there is no next year for quite a while.