It's a shame nobody mentioned the impact of the Mac OS X Aqua interface on all of this.
Aqua was the name Apple gave to the user interface style introduced in Mac OS X. He changed the Mac software as follows:
… To look like this:
This is Steve Jobs's first introduction to MacWorld San Francisco 2000. As he says
One of the design goals was when you saw it, you wanted it lick it,
There is no doubt that a big influence on the appearance of Aqua with all its delicious buttons, pinstripes and its transparency was the great popularity of the iMac:
Aqua was a big change in the UIs; They were no longer drawn by the operating system, but mainly as layers and layers of bitmap (or even vector) graphics. Windows XP followed the same idea in 2001. Your Luna user interface looked like this:
When it was released, Aqua made a similar splash as the iMac when it was released. It felt like every single element of third-party designers would have had some unnecessary shine over the next five years:
Despite the popularity of translucent and glossy plastic aesthetics, Apple's hardware designs have increasingly withheld over time:
The unstoppable march of material design, simplification and style of hardware had a similar impact on the software – with reduced transparency, diminishing visibility of the pinstripes until they completely disappeared, introduction of brushed metal interfaces, to something else to the old, predominantly gray interface of MacOS 9:
This change is neither specific nor specific to the Mac. It happened throughout the industry.
In the meantime, iOS was released (called the iPhone OS at the time), which looked like this:
And as you almost certainly know, the iPhone and iOS itself have been hugely successful. Many, many applications (including Skype) have been released with the glossy symbol overlays to be appropriate alongside these symbols.
Just as Mac OS X looked exciting and refreshing for years, this screenshot of the original iPhone OS screen is now 6 years old and looks like this:
As you can undoubtedly see, there has been an unusually slow progress when it comes to the look and feel of Apple's mobile offering.
The old adage is something like this:
If you do not improve, go back
And so two of Apple's key competitors in this area (Google with Android and Microsoft with Windows Phone) took the opportunity to do something radically different and improve the state of the art themselves. make it look like this:
Update: I just thought I would add a little bit more to the Android languages "Holo" and Metro and how designers and designers describe the flatter, less shiny aesthetic:
When it announced the metro design language (or what it now calls the "Microsoft design language"), Microsoft made some thinly veiled jabs on Apple's shining iOS aesthetic. They also claim that Metro's flatter, more typographic design style is "more honest" and "authentically digital." On the Windows Phone Design Principles website, Microsoft expressly states:
Create a clean and focused experience by leaving only the most relevant elements on the screen.
When designing great app experiences, we believe in content, not chrome.
Concentrating on content on Chrome reduces unnecessary content to make the content of your app shine. Let people immerse themselves in what they love and explore the rest.
You will realize later:
Being authentically digital means going beyond the rules and characteristics of the physical world to create new and exciting possibilities in a purely digital space. Make full use of the digital medium.
Be "infographic". Providing information is the primary goal, not the wrapper. By using the infographic approach, you can optimize the user experience on Windows Phone
Regarding the redesign of their logo, Microsoft relies again on the grounds to be "authentically digital" to eliminate the glare:
It was important that the new logo carries the metro principle "Authentically Digital". By this we mean that there is no attempt to simulate faux-industrial design features such as materiality (glass, wood, plastic, etc.).
Unfortunately, Google did not make their intentions when creating Holo very clear. While they have definitely moved strongly towards the so-called flat design style, they have not made it very clear why. With regard to symbols (which form the core of your question) they simply say:
Use a unique silhouette. Three-dimensional front view, with a slight perspective as seen from above, so that the user perceives some depth.
However, they go deeper into their developer documentation where they say (highlighting mine):
Icons should not be cropped. Use unique shapes if necessary. Remember that startup icons should differentiate your application from others. In addition, Do not use a shiny finish unless the object is shiny,
Their earlier design guidelines from Gingerbread and earlier versions (i.e., Pre-Holo) also explicitly mention the texture ("Icons should contain non-glossy, textured material"), with the full description of the materials described as such:
Launcher icons should use tactile, textured materials with top light. Even if your symbol is just a simple shape, you should try to render in a way that makes it appear as if it's made of a material of the real world.
Android Launcher icons are …
- Modern, minimal, matt, tactile and structured
- Forward facing and illuminated from above, limited in total to the color palette
Android Launcher icons are not …
- Antique, over-complicated, shiny, flat vector
- Turned, cut off, oversaturated
Clearly, Google and Microsoft intend to use the latest mobile operating systems to avoid the aesthetics of iOS / Aqua / glossy.