Are you saying Inter Milan had a strong team last season under Simone Inzaghi? A team who couldnt win a single title last season, they got knocked out in the Coppa Italia semi--finals, lost to AC Milan in the Supercoppa Italiana finals, finished second in the seria A table and shamefully lost to PSG in the champions league finals.
They are not the champions in those competitions but it's wrong to say they are not a strong team and surely I disagree with you on this point. They lacked of something to win Scudetto and Champions League title but you know everything can change in such situations and the verge between champion and runner-up is very small.
You can not say a team that fail in a league with a runner-up position and a final match in Champions League is a weak team. Even if Inter Milan meet PSG again, nothing to be sure that PSG can beat Inter Milan, and this slim difference means Inter Milan are strong.
Christian Chivu might not be the perfect choice but giving change a try isn't a bad decision especially in a time as this where Inter need a trophy to clear their high debt and accumulated interest burden.
Now, they take high risk with a young coach like Chivu and reasons behind this important but dangerous decision can be money. I don't know about Inter Milan's financial condion but from this bet, I feel like they don't have too good finance and don't want to take risk with better coaches as replacement for Inzaghi.