Those ring proofs are still available (somebody is saving them) if we need to reconstruct from a discovered bug. In the meantime, no need to force everyone to download them every time we sync, which is a significant problem for XMR as I've read some users complain.

And if you think about how to radically decentralize mining as I have been doing for months, then you will realize a long download time for syncing is a significant issue.

(I repeat, "the jury is still out...")