"Sure, but at what cost?"

At the appropriate and necessary cost.

A less costly new engine design or less costly engine swap procedure that fails is worse than no airplane at all. If it's cheaper and fails, we don't want it. It wasn't cheaper, it was even worse than expensive.

It's not hyperbolic all or nothing. Sure infinite cost is just as useless as infinite failure, but there is no reason to talk about infinite.

At what cost? Some. At some cost.