CC was just unnecessarily shoving Zack/Aeris down our throats.
I mean if you're trying to even leave the possibility of Cloud/Aeris open...you don't add shit like Aeris using Zack's lines on Cloud, or that he told her to wear pink, or that he was the one who bought her the bow, or that he was the one who got her to sell flowers, or that she continued to write letters to him for YEARS, etc. etc.
Why?
All in the past? Fine, except we already knew she had an ex who was a SOLDIER. Why not leave it at that? Why not leave it at "it wasn't serious"? Why not show their relationship without trying to tie it to Cloud?
Maybe without later adding things like "Aeris acted the way she did around Cloud because of Zack"? Maybe without having Cloud put Zack's Buster Sword through Aeris' flowers in ACC. How about not having her appear in probably the most pivotal scene and make her final exit with said ex? Whom she was totally not serious with, but still wrote to for years after (89 fucking letters and no reply).
Damn it, SE, what are ya trying to say?