It is just straight, boring color without any other details.
Compare this
to this
and you understand what I'm talking about.
Please add something in background that makes the icon more interesting, like I don't know, sunshine? Sand?
For Shurima we had this when Ascension came to be:
http://i.imgur.com/wEt9cpb.png
And this for the SI:
Not an excuse for making the next ones less flashy but it might be that they didn't want those icons to be too similar and opted for something less shining.
Fun fact they hate 
Targon's is the most detailed out of all of them while the Freljord and Shurima look blurry and low resolution.
Propably cuz they're older icons. They didn't make them from scratch.
