Observed in a vacuum, I don't think there's anything particularly wrong with Ferrari's approach or output, especially given the complexities imposed by the new technical regulations. But, by the sport's very nature, teams in F1 don't exist within a vacuum; they compete against one another, and Mercedes is simply on another level.
And why shouldn't they be? By some accounts, they've
spent upwards of €500,000,000 over the last couple of years in order to mount
this challenge, right
now. On the other hand, Ferrari and Red Bull, and by extension, Renault, have been busy competing for Championships.
It's a lot easier to keep an eye to the future when there's nothing worth looking at in the present, and Mercedes is now reaping the benefits of several years spent within such a paradigm. So, give them their due. It's no different than Red Bull's strategy in 2007 and 2008 to gear up for the change of regulations in 2009. Driven by expectations, both of itself and from its fans, to compete on a yearly basis, Ferrari has never had that luxury. The only other team with such a philosophy is McLaren, and Ferrari has consistently outperformed them over the same period of time.
I guess my message is this: relax. The power units are homologated, which means teams can only optimize what they've got. Despite rampant speculation to the contrary, there are no 900+ bhp monsters driving the Silver Arrows; they simply have their power units more sorted than everyone else at the moment. But, things change. And if Ferrari's wind tunnel woes are, indeed, finally over, things can change rapidly.
Remember 2012.
At least, these are the things I'm currently telling myself. Your mileage may vary.