Wouldn't it be a good idea to add gizmos to the game-view/game-build as well?

It's great for debugging in-game but it can even be used as part of the art (for selecting objects for example, like Deus Ex does)...

you should request features in feedback.unity3d.com or talk about them in forums. now you can draw gizmos in gameview. you just need to press the "gizmo" button in top of gameview. you can not select objects with them in gameview but you can see them and use them for debuging.