The supposed engineering flaw is that it was not made to work without the additional 40 bytes of OP_Return output? - by using which, Counterparty was going to wreck havoc on the Blockchain and ruin the ecosystem for Full Nodes (which have been storing 18gb for free all this time and would have to deal with an additional 5+ mb of prunable data?).

(regarding Class A) I don't think that anyone is actually going to store data like that, it looks more like it was a proof-of-concept - probably not the best way to move this discussion forward though..-