Flat design is basically the response to skeuomorphism. Essentially, you can look at it as a rejection of skeuomorphism, which is design that features 3D elements such as drop shadows, gradients and textures. Flat design stresses 2D elements that include things like bold colors, sharp borders and a clean, minimalist design overall.
The thing is that the more complex and colorful your logo will be the more it will look like a toy and less professional. the idea of clean logos is driven by that feeling that you can simplify something and make it appear strong. this is the true art of doing it right. It’s one thing to make a logo, this is something anyone can do but to get a logo that leaves an impressions and that is extremely simple is something completely different.
Learn more in this article on Flat design Logo’s
and Make sure to watch this video