Point 1. There was a cost and a benefit to having an opaque and developing Brexit policy as opposed to a fixed and clear one from the start (eg what they have now or a simple revoke policy).
Part 2. There were also further costs and benefits associated with the speed and management of developing/clarifying the policy over the last 2 years.
On point 1, I think you’d have to be an idiot to think they chose the wrong option on balance. On point 2, I think there are valid criticisms that might end up being decisive in the final GE result.