I was confused by the technical aspects for a bit. Now I'm confused by the people who understand the technical details and oppose the change.
The core teams public relations on the subject has been terrible and I want to oppose just over that but emotional reprisal isn't a good plan.
So why make the most prunable data the most expensive place to put spam? Full archival nodes are all storing 4mb/10m either way. This reduces block size for pruned nodes assuming the arbitrary data people do go for it.