As to why Trump doesn't just ignore the courts: it gives ammo to those who may try the impeachment thing again ("He defied a court's order!!"). It appears the Administration's strategy is to go down the "malicious compliance" route for now, knowing this will likely reach a boiling point to where the SCOTUS needs to step in and clean up the Judicial Houses. I'm not sure what the mechanisms that Roberts could use, but all of the district courts fall under his authority. Roberts and Barrett are not necessarily going to side with the liberals, rather they like the idea of the appellate process and not have parties skip the steps along the way. That being said, with all the cases in various District Courts and multiple Districts, the government's position is essentially the same in all cases (Presidential authority vs. Judicial standing and review) that might force a consolidation of all the different cases into one appeal to SCOTUS which would be hard for them to deny getting involved.
If SCOTUS doesn't get involved and clean their own house, there's already a couple of bills and resolutions in the House to start with the "Cleanup on aisle 5".
And if John Roberts wants to imply that the courts are fair and impartial, I would challenge him to have every one of these cases moved to different districts in places like Utah, Oklahoma, Texas, etc. I'm fairly sure we wouldn't see nearly as many (if any) ridiculous rulings usurping the Executive's authority.
