Ah, the curse of the rookie WR... all that promise but none of the production. Johnson, no matter the hype, isn't going to make a major impact this year. WR's don't typically hit their stride until year 3. Johnson might be the best rookie WR in history, but that still doesn't justify believing that he'll be a top WR.
Remember, draft with your head, not with your heart. Even if you are a GT fan, that should have no bearing on who you take in a draft. I'm a huge Steelers fan, but I don't have a single one of their players on my team. If you are in a keeper league, it's a different story because of all the potential that Johnson offers, but otherwise, he's only going to disappoint this year. Get what you can for him and wipe your brow, content in the knowledge that you didn't suffer all season with a rookie WR.