Currently spells (in particular aggresive spells) can only be cast when you have a target selected.

If you compare this to regular weapons which can be cast with no target, this seems odd to me.

Apart from the fact that it would just be fun that you could cast whenever you want to, it would also add the same playstyle required from normal weapon users.

At this stage it seems to me that this could even be regarded as an advantage over regular weapon users because they can just hold their button down and wait for their mouse to hover so that they can shoot.

If they miss their crosshair their fire simply stops until you hover over them again.