Like my marketing professor used to say:
If everyone in the market is advertising toothpaste with sweet minty taste. You better advertise a toothpaste with salty taste. If everyone is advertising with flouride, you better do one without flouride!
i.e. Think Different!
Basically it's a marketing trend. All about standing out from the others. Now that market is saturated with glossy finish products, matte is back in.
There are and always will be merits & demerits for each, and they will each be suitable for different tasks. There is no particular reason, the masses don't think too much, they just follow the leaders. :)
A better question would be pros/cons of glossy vs. matte look. A simple answer would look like below:
Glossy
Pros:
- Attracts the eye (bright, shiny)
- Illusion of depth
Cons:
- Overused?
- more complex to produce (more resources, be it time, money, cpu cycles ...etc.)
Matte
Pros:
- Not Distracting (can easily glance over it)
- simpler to produce (less resources, be it time, money, cpu cycles ...etc.)
Cons:
- Overused?
- Not attracting attention?
As you can see this is an overly simplified list. A quick google search didn't find any links showing such results. A good chance for the UX community to get together and make one! Time to wiki it!
See the Google trends for matte vs glossy.