I like this argument, but it doesn't address Rook and Crosswise, who of course were Minicons that came with an Armada deluxe toy. Their only value is either together as a combiner, or as headmasters for Sideways. Dead End that came with Unicron could probably be included too. If we count them (even though they are the outliers of the Armada minicons), then I think we should count the PCC minicons.
Perhaps it's worth amending Articles 2 and 3 to accomodate this new argument about "independent play value", rather than creating arbitrary and unwieldy (albeit democratic) exceptions.