What "looks right" today looks out-dated and clunky tomorrow. There usually isn't any logic behind it, only changing tastes.
Flat looks/ed good because we were so entrenched in a skeuomorphic world and were sick of it. Just like wearing baggy jeans with teens morphed into skinny jeans, or grunge music supplanting glam-rock, tastes of humans change over time and no matter how hard you try to break it down and analyze why one art replaced another, there isn't usually an answer to be found.
Extreme flat design has brought about horrible interfaces (see iOS7) yet it has also brought wonderful innovations due to it's tendency to break free of the physical world.
Were gradients and company names without vowels of the Web 2.0 era superior to the ones prior? No, but it felt right because of where we had come from. I suspect that trend will continue forever.
There wont' ever be a "final" design aesthetic that we all agree is the best, and art will never reach some sort of pinnacle that will never be surpassed.
Make your own art, don't worry about what is trending ... you might find yourself on the "right" side of design if you focus on making your art the best it can be.