The launch tower takes multiple months to build. The orbital launch mount and launch tower and quick disconnect hardware is all custom and expensive and huge. They call it “Stage 0”. Losing that is an order of magnitude more of a setback than losing a Stage 1.
Why not to use the Mechazilla for adding the next section of tower on top of existing one? So we transport parts to the tower, assemble relatively thin sections of tower nearby, the lifter moving along the tower brings the sections on top of existing ones, and we have a few places for optimizations here. The proponents of The Boring Company may see some parallels here.