The change to PAYG was due to the fact that lots of people found our “plan costs $X/month and comes with $X/month of included usage” confusing. And the convolution of free allowances, included usage and <$5 invoice waiving were baffling to many. By comparison, PAYG is very straightforward.
I’m not quite sure what you mean by “Legacy Legacy” and “Legacy”. I think you’re alluding to the fact that previously it was possible to never consume your trial credit, because the free allowance would be consumed first? This was a limitation of our old billing system; our intention was always that the trial would be a one-time $5 credit.