Philosophically or practically: What's the justification for nearly everyone switching to flat design? Is there any articulable reason it's "better" than the rich, three-dimensional style[1] that was previously popular? Or is it just an arbitrary trend?
Some say the change is driven by high-DPI displays. I disagree. I don't see any intrinsic reason that flat designs look better than rich, three-dimensional designs on a high-DPI display. Without a doubt, flat can look nice, but so can things like this:
Another justification I've heard is that it's a reaction to the excesses of the previous trend. People often point to the leather motif in certain Apple applications as an example of such excess. But first of all, those examples are outliers; few designs actually went that far. Second, the existence of a questionable use of a given style is not an effective argument against that style in general. Third, "some things were extremely 3d, so now we'll be extremely flat" seems like contrarianism for contrarianism's sake.
[1] Some call this skeuomorphism. I tend not to, because the term technically means something narrower than what we're talking about: http://en.wikipedia.org/wiki/Skeuomorph
Frankly, I don't care about the look of the icons (these should be theme-able anyway), but I do care a lot about the actual application user interface, and for this, flat design is a step back into the 80's.
Flat design is good as long as there are no important visual cues lost what elements can be interacted with and which are just passively displaying information. I really do still have problems in iOS7 to separate passive text elements from interactive text elements (formerly called "buttons"). Examples are the contacts list or the famous shift-button of the onscreen keyboard.
Thankfully in OSX 10.10, buttons are still recognizable as buttons, and I like that less radical flatness much more then iOS7. Although, in the current state the UI looks a lot like a Gnome skin which tries to mimic OSX though, I hope that improves until release.
A lot of it is flat, but they use simple bevels for buttons and other clickable elements, and its reuse on, for example, the buttons in the file manager window, looks tacky because it appears cluttered and overused. Also, excessive lines (e.g. for the window borders), high contrast colors, and small color pallet makes the overall appearance not nice to look at. Also the icon set suuuuucked.
'3D' UI elements were introduced later in AmigaOS2.0, and I remember how the user interface style guide made a big fuzz about how UI elements that appear raised are supposed to be clickable while flat or recessed elements shall be used for non-interactive or disabled UI elements which cannot be interacted with.
Actually this site is a pretty awesome collection of operating system UIs. BeOS still looks nice, almost like retro-modern pixel-art.
Older UIs like the Amiga OS one suffered from an even more limited pallet, and even worse typography.
I used BeOS as my main OS for a while and really liked it - it was very snappy and felt more "homey" (that is, more like classic MacOS) than early OSX versions did. (The browser, NetPositive, was absolutely awful though).
pro-3d / anti-flat: details made possible by volume add to the icon's rich design, making its personality stand out, while flat icons results in boring, uniform design in comparison.
pro-flat / anti-3d: the apparent uniformity makes even slight nuances readily apparent and efficient to parse, making each icon stand out against other flat icons, while 3d icons are full of complex and distracting artifacts.
Bottom line: don't mix both, as the result is that 3d crushes flat with its rich details while flat makes 3d look needlessly busy and noisy. Consistency is key to reducing cognitive friction.
I think 'flat design' is really just an example of minimalist design (which has been around for ages) applied to graphical elements. With many things, especially apps/websites, minimalist design often ends up being a good experience for users because it's not distracting, but that's not to say that you can't have great UX without a minimalist design.
For me, I like flat design (to an extent) because it gives the product a more uniform look and feel, but sometimes it can be overdone and I find myself wishing there were an illusion of depth to guide me.
> With many things... minimalist design often ends up being a good experience for users because it's not distracting...
As long as too many cues aren't discarded (iOS 7 went a bit overboard in this regard) I completely agree; shiny or complicated visual elements with "pop" demo well at first but become tiresome.
It's the same reason our keyboards don't make musical tones like they did in Star Trek -- it would quickly become distracting and annoying.
Since the Aqua look came out in OS X, there have been a lot of imitations used on webpages, knock-off UIs, etc. which tended to look terrible, in part because it's hard to do them tastefully. At least flat UIs are harder to mess up.
It's a fad. Apple came out with it 'first', making it automatically used among millions of people, then designers followed with other software packages and apps.
Yep, but that's how it works. A year ago, people were complaining that Apple sucks because iOS was still using skeuomorphs instead of flat design like Android and Windows 8. Now they've switched their style, and they suck because they invented flat design and everyone is just copying them.
Gradients and juicy-fruit graphics are like candy -- they provide an instant and strong positive feeling, but they don't age well. If you had to eat nothing but candy, you'd hate the sugar-coated morass your mouth had become. In general, a flat icon tends to age better and reduce "eye exhaustion" (not a physiological thing, but a psychological one). Note that this applies mostly just to icons; the entire UI is not so tightly bound by these rules.
However, design is also trend-oriented, and flat is a rising trend.
Some say the change is driven by high-DPI displays. I disagree. I don't see any intrinsic reason that flat designs look better than rich, three-dimensional designs on a high-DPI display. Without a doubt, flat can look nice, but so can things like this:
http://www.sequelpro.com/blog/wp-content/uploads/2013/01/seq...
Another justification I've heard is that it's a reaction to the excesses of the previous trend. People often point to the leather motif in certain Apple applications as an example of such excess. But first of all, those examples are outliers; few designs actually went that far. Second, the existence of a questionable use of a given style is not an effective argument against that style in general. Third, "some things were extremely 3d, so now we'll be extremely flat" seems like contrarianism for contrarianism's sake.
[1] Some call this skeuomorphism. I tend not to, because the term technically means something narrower than what we're talking about: http://en.wikipedia.org/wiki/Skeuomorph