Either you've watching the wrong season or you're being ignorant.
Massa isn't perfect either. Look at Canada, he refuse to take the blame for his mistake. In France, he blame back markers. Alonso instead admit that his car was two slow and refuse to blame backmarkers when asked to comment on them. He also said it's the same for Kimi so the back markers makes no different. And that's why he's a 2 times world champion.
Kimi is doing his job just fine. If he isn't helping the team developing the car by actually driving it during testing, he wouldn't have been able to learn how to use it the way Michael always do with attacking the lap times when it matters most.
Just because Massa is slower and made a mistake in the past couple of race, it doesn't meant Ferrari is developing the car around Kimi. Why not face the fact that Massa made mistake? Kimi is different from Michael. He and Massa came into a team which is already at the top. Michael came to a midfield team, build the team back up to its winning ways and go further by winning them 5 championship, keeping Ferrari up there for as long as he could.
So why complain when Ferrari builds their team around their one and only hope season after season? Eddie had the chance and he blew it. Rubens is nowhere near championship material. If Rubens could bring Honda back up to the top and win the championship, I'm 101% sure Honda will be build around him. Will anyone complain against Honda then? I though so too

Unless you're working in Ferrari factory, you can't simply accuse them to be building the car around Kimi, just because Kimi is winning now. If you don't like kimi, too bad then but it still doesn't change the fact that Kimi is a good driver.