I'm not sure how you're using the word 'optionality' here, but I get the gist. I think that all retirement plans - DB, DC, and variants thereof - try shifting risks around to improve outcomes. But fundamentally they don't really get rid of risks, they are just shifted from one sort of risk to another. In the case of a DB pension like I'm talking about, the individual has no market or longevity risk, but they have some institutional/policy risk and reduced control. DC funds try to eliminate the chance of your pension being underfunded or the funding organization going under (and gives people more control), but it adds a lot of other risks onto the individual. IIRC there was a nice piece about this a while back but I can't find it right now; I'll see if I can get it later.
My argument isn't that one side or another isn't without risks - there are always risks - but that by diversifying the type of risk one is exposed to, it decreases the chance of wholesale catastrophe to one's retirement savings.