Technically we don't really know to what extent the extraordinary events of late 2017, where we saw large and sustained overvaluation of SBD, would ever recur. So far we have not. There are already some improvements to SBD since then: 1) printing does not slow and stop at the very low 2-5% ratio any more, and b) SPS offers a large-ish ready supply of SBD which can be introduced into circulation by stakeholder vote (one way would be using SBD from SPS to buy STEEM and then burn it, as you stated, though this is still limited by the supply in the SPS treasury).

That being said, I also agree we should improve SBD. One way to do this is by further leveraging SPS: https://steemit.com/steem/@smooth/steem-improvement-proposal-allow-steem-donations-to-the-dao