1. Although she has great limit breaks, she still dies not even halfway through the game hence rendering those limit breaks futile.
2. She may have a specialty over magical attacks but the Walled Snake boss at the Temple of the Ancients (where Aeris is a mandatory character) has rampart defense against magical attacks, again rendering Aeris futile.
3. How can someone so pure be so flirtatious over the guy she loves and in front of another girl who loves the same guy?
4. And the way she never considered Barret's feelings at the Gold Saucer. All she said was "Let's have some fun!" not even caring how bad Barret's mood was that time regarding his past towards Corel.
5. She may be 22 years old but still acts so juvenile. Far more sickening than Rikku from FFX-2 IMO. She's older than both Cloud and Tifa but the two former act more maturely than she does.
6. And basically, it was Tifa who actually cared. She held Aeris's hand when she died. And even after Aeris expired, Tifa still reminded Cloud of her in her memory.
7. And besides, Aeris never loved Cloud because of his natural being but because of his resemblance to Zack. Basically speaking, her feelings for Cloud are merely a reiteration of her feelings for Zack.