1. Again did you miss the part about adding Griffin in free agency. You make the trade for George after you sign a free agent.
2. And Wiggins was a far better prospect than Fultz at the time of the draft and was in what was considered an even better draft at the time of the draft.
3. Why do you assume George wouldn't sign in Boston long term in that scenario?
4. George is better than Love.
5. Do you think Fultz will ever be as good as George and if so how long does it take?
6. who are you trading and for what to get Fultz playing time? All the guards can't stay. There aren't enough spots available.
Having Griffin on your team doesn't guarantee you'll even have him for the playoffs, let alone title contention. I don't think that's a reasonable pre-condition to giving the go-ahead for trading a #1 overall pick for an expiring contract player who isn't even All-NBA and who has made clear he will explore his options in FA.
I can't assume George wouldn't re-sign in Boston, but my sense of him and my reading of what has been put out there in the media by his team / agents etc is that he will absolutely consider his options and will probably want to get to a major media market.
To me, the risk there is just too great to justify trading the #1 overall pick in a strong draft with a really good consensus top pick, let alone throwing in two quality cost-controlled role players on top of that.
As for Wiggins, his outside jumper was a big question mark. Still is. His ability to create plays for others was a big question mark. Still is. His ability to defend at a high level was a big question mark. Still is. His ability to make an impact on the boards was a big question mark. Still is.
Wiggins has developed into a nice individual scorer, but he has yet to progress to the point where he elevates his team.
Markelle Fultz is considered a very good shooter who can also make plays for other and serve as the primary ball-handler. Defense is a question mark for him, and he doesn't have the same size or physical tools as Wiggins, but I like him much better as a prospect for today's NBA. Wiggins seems most comparable to Demar Derozan in terms of his overall skillset and impact.
Of course George will explore free agency because he will make more money in free agency even if he re-signs with Indiana (now that the super max extension is off the table). Plus, he is playing in Indiana which isn't exactly a winner (not a loser, but clearly a couple of big time players away from being a contender). George has made it clear he wants to play for a winner, Boston in that scenario is winner.
I think you are misremembering Wiggins scouting reports at the time of the draft. Here is the draftexpress scouting report.
http://www.draftexpress.com/article/Andrew-Wiggins-Scouting-Report-and-Video-Breakdown-4414/ Of note this what they said about him on the defensive end of the court, "Defensively, Wiggins is already extremely effective. His combination of size, length, lateral quickness and solid intensity gives him the potential to develop into a multi-positional lockdown perimeter defender in the NBA, particularly as he matures and gets stronger." Now obviously, this hasn't exactly been borne out in reality, but Wiggins was thought more of as a potential two-way player with unrefined yet extraordinary potential offensively that would be a very strong defender and would be that almost immediately. He obviously didn't pan out like that defensively, but has certainly shown tremendous offensive potential.
Fultz certainly has the potential to be a great player, but even if he hits it all 100%, he is probably a Westbrook type player, which is great, but not a guy that is going to lead a team to the promised land (I mean can you see a Westbrook led team getting to the conference finals if they even can make it out of the first round - and look at the Clippers with Chris Paul, no conference finals for him either). Now sure, maybe Fultz, Brown, and BKN 18 all find that perfect mix and are a title contender for years, but how far away is that from happening and how likely is it that all 3 hit their potential (SEA/OKC striking gold with Durant, Westbrook, and Harden in consecutive drafts is extremely rare and they added in guys like Ibaka because they sold off players for draft picks)? And if that is what you are relying on, then what is the point in hanging onto Horford, Thomas, etc. since those guys won't be your title contending core?