Messi situation is tragic. I love Messi (I always watch PSG game snippets for the fragments he's in) and ideally he should come back tomorrow and retire at Barcelona, but this is not an ideal situation and his return seems like a problematic distraction for the moment.
Let's remember Barca's famous collapses with Leo on the pitch (Rome, Anfield, Munich) and it will become clear that even his unmitigated genius cannot save the wobbly Barca from spectacular catastrophes. I would also prefer not to see Messi overburdened with responsibilities and expectations. This could end tragically for the player and his legacy.
Not to mention the well known truth that "you cannot step into the same river twice". This kind of return carries an enormous risk for everyone involved. Reintegration in a newly formed team is one of them. Surely Messi is still a brilliant play maker and could fit into Barca midfield but who would the club have to bench then?
Barca cannot afford to make gigantic financial effort to make up for the past wrongs. Xavi's project is still erratic and vulnerable and the team's backbone is still wanting. The scan resources that the team has should be allocated in bringing in solid players that can fortify the team's weakest spots in the next season. Shall Barca generate funds for Messi's salaries by rushing to sell young and yet unproven players that the club bought few months ago or recently promoted from Barca academy?
The only way I can see his return justified at the moment is an economic miracle before the summer transfer window. Perhaps Barca can do a one-time socios crowd funding to bring Messi back? That would take some economic pressure away from the club and make his return "sponsored" by the members.
I am also not enamoured by Messi's sponsorship deals with the Saudis. His flirt with the murderous monarchy is a dark stain in his biography. He's a brilliant guy. He should be able to make the right judgement.