Complete rebuilds have fallen out of fashion. When was the last one that actually worked? The downside to a big rebuild is far, far greater than the upside.
The current playoff structure also favors a retool approach with the goal of making the postseason. It's not worth fighting $200+ million payroll teams for a first round bye.
The 'ideal' scenario is that retooling is a constant process, there are constantly younger players waiting to step up. Unproven talent doesn't always live up to expectations -- the Rays have certainly gotten worse at SS in the short term without Willy Adames around. However, the Brewers' pitching core isn't getting any younger and will continue to lose both actual value and trade value with every year that passes by.
At some point it comes down to your trust in management's ability to evaluate and grow talent. On one end of the spectrum, if you had zero confidence in the Brewers' organization, it would be an easy decision to want to hang onto our current talent as long as possible. On the other end of the spectrum, if you had full confidence in every highly-ranked young player turning into a stud, it would be an easy decision to cash out and replenish the pipeline, even if it meant getting worse in the short term. The 2022 Rays certainly seem to be suffering from the "got worse in the short term" reality, although the rest of their division getting better isn't helping either. And they will probably make the postseason anyway.
Personally I feel that the Brewers operate with an opportunistic mindset and they are not going to lock themselves into one extreme or the other. I could easily see them signing Burnes to a long-term extension and trading Hader in the same offseason, depending on their take on the market and the projected value of their various assets. In the Melvin era it felt to me like management was rigid in how each asset fit into their plan and was strongly biased toward short-term goals. In the Stearns era I feel like they operate more on a set of principles vs. having a plan for any particular season or asset. When the opportunity comes along to make a move that will further either their short term or long term goals, they won't hesitate to make the move. I think they have a general plan on when they would trade or extend Hader/Woodruff/Burnes, but their main principle is flexibility, and they will quickly evolve to the rapidly changing (and unpredictable) landscape of MLB. We don't even know what the rules will be in 2023!