That would be good if you have not an island but a castle like in Worms World Party or Worms Reloaded and add possibility to buy some decoration stuff on it.
I want also to move my worms around the place and maybe put them in the... hands(?) some weapons to make it more attractive to visitors.
Moreover that would be good to make some world map where players or groups could occupy lands and owned some bonuses to money from that.

It looks like this will be possible anyway. There is a "my island" section in the shop (not accessible yet).

I agree, I think it would be cool to buy props for your island like each of the game-world objects we see in the levels and then allow us to flip, scale, rotate and position them to make our island unique?

There will indeed be an island shop in which you will be able to get more themes, scenery objects / props, etc to use for your Home Island (including pieces to build into forts of your own). And you'll be able to flip & rotate objects to your heart's content :p