First, again, they go to the center when they lose. If they don’t lose, they don’t need to go to the center to find voters.
Second: They will do what people voters want. That is the whole point, voters. Right now the voters are voting for brutally slow progress. That’s what they get when they give Dems control of all 3 for only 4 years every 24 years. Want faster progress? Then be the voters that vote for faster progress by giving Dems consistent and overwhelming victories.
In addition to that, I really think Dems want left policy. They do it when they can despite it costing them elections. According to your logic they would never have done the ACA, or green energy, or EVs, or union empowerment (inb4), or student debt forgiveness, or Chips act, or Pact act, etc, etc. But they did, and it cost them.