You can make a macro to change between your specs so with one button you insta-change. For exmple, you go with dps in the field doing quest, and you change to healer to get some health back, then back to dps to continue.
Or maybe we are in raid and we have to switch between interrupt armor build and normal dps build for some pulls, who knows
So you need:
1) Open macro menu (lower left button of wildstar ui, then search "macros")
2) New
3) Name: Whatever you want, "Next Spec" should be enough
4) (Optional) Assign an icon to this macro (click in the square to the left of the name)
5) Paste this text in the macro text field:
/eval AbilityBook.NextSpec()
6) Press Ok, and drag your macro to the action bars
Enjoy