Yeah,we understand Aguero is in Barca to make tittles,but one of his motivating factor to come to Barca was the fact that he was going to play with Messi,the world best player.And now that Messi is no longer in the team,it would be even hard for Barca to even win a major tittle,because the team was built around Messi.
Messi was a key player in Barcelona, he never wanted to leave the team. And that is why he drop his salary by 50%, but unfortunately, Barcelona currently is not financial strong. No doubt, Aguero is talented and will probably play well in Barcelona. But he wanted to play with Messi. I don't think Barcelona squad will be strong without Messi, winning Major titles won't be easy for them.