I don't think that that would qualify as a symbiotic relationship - you can't get Mindwipe direct from retail anymore, you'd be buying him from a fellow fan or Internet reseller, so it's not like Hasbro would be part of the transaction. Skyhammer is newer so you may have a bit more luck with him but the point still stands.

Even if head robots were making a run of 10000 heads, which is 5-10 times as many as they make, and all of the 10000 people buying needed a fresh Skyhammer or Mindwipe it still wouldn't be enough of a profit to justify Hasbro shoe horning them in to one of the existing lines again.