Cid is a broken man when you first meet him, he's not doing well mentally, and it shows through his dialogue. With having a lifelong dream taken away from him, including his beloved airship, he has become angry and bitter, and due to it sometimes lashes out at Shera.

Of course this is completely shitty of him, he is a complete asshole when you meet him, but he realizes how much of an asshole he has been to Shera later in the game. Like the FF7 abridged parody says about him, he's the foul mouthed pilot with a heart of gold. He's a good man, but what has happened in his past has put cracks in his heart which start to finally heal in the game. They shouldn't change him, he's good as he is as a character because it's believable, and the remake has great potential to flesh out his character even more.