[...]what for can a mobile wallet be usefull ? specific examples i need 
[...]
[...]Pocket money. So you can actually use your moneros on the go instead of needing to be at home.
It is like having a quickly accessible photo camera on your mobile phone, instead of a high performance one but always in your desk's drawer.
now we can finally, on the spot, sell someone 5 usd of XMR without having to tell them they have to go home, log in their bank acct, and buy some bitcoin which they have to use to buy XMR. Which they never do because its too damn hard.
There are many people with small money interested in investing in XMR, it just need to be easy enough.
Great, I thought it had to be something like this