How many top attackers do you want in your squad at the expense of everything else?
This isn't football manager of FIFA mate. (As much as people throw names around freely like it is.). Adding another vet. attacker, as top notch as he is, isn't fixing the multitude of other problems they have when they're trying to rebuild.
I know. Believe me, I'm the one who advocates the most against FIFA/FM changes. But they need Griezmann. Suarez is declining, and has not been present in the CL at all this season. Dembele on the left/right is extremely inconsistent. Malcom is not trusted/played by the manager. Coutinho has under-performed massively, so much so that the rest of the team are literally carrying him.
Assume they sell Coutinho/Malcom (which by all reports they want to). They will want one top class attacker to come in, who can play across positions, and who can score enough to reduce the burden on Messi, and give opposition defenders one more headache to mark. Griezmann literally ticks all those boxes. Plus, this means they can get Griezmann to lead the line eventually, along with MEssi (or Messi on the right).
They have other problems, yes, but they are on the way to fixing it. Attack is where they needed the most obvious quality addition. They already have the rebuild on with a young CM (de Jong), who, depending on the need, can play either the Xavi or the Biscuits role. Alena is coming through and they already have Arthur, not to mention Rakitic. CB, yes, especially if they get de Ligt. If not, you have to think they will persist with their current pairing to see if Umtiti can go a season uninjured. If so, reasonably solid there. An aging Pique, sure, but yeah, he can probably play at the top for another season.
Fullback is a concern. RB, you have to think that Semedo will get another season to impress. The main glaring hole seems to be at LB, where they need a very good rotation option for Alba. Otherwise, Barca seem sorted, reasonably atleast. Isn't as massive a rebuild as the likes of Madrid, Bayern or us are facing. Don't really see the fuss with Griezmann.