Cool concepts in comics that never met there potential
Cool concepts that you like, but execution was bad or they never developed into anything of importance or relevance.
Some examples was Anti-Venom. I thought the idea of turning Brock into a good guy and giving him a good Venom evolved suit, was interesting concept with potential, but was executed poorly.
Another Example was that of giving Harry Osborn not only a goal to put his father down, but also giving him a super soldier like serum and a suit, but this idea really never to my knowledge developed into anything.