Ah, so it's the pressing enter after clicking the spell that bugs you. From my understanding, removing the aoe toggle won't get rid of that extra enter press. If you want that gone, SE would have to take out the ability to target someone else with a spell besides the target you have main lock on.
The current system as we're all familiar with goes:
1. Select a target to bring up abilities list
2. Select a spell
3. Confirm target for the chosen spell with the option of toggling aoe.
If we wanted the extra enter press to confirm target to be removed we'd have to change the system to something like:
1. Select or change to target which you would like to cast the spell
2. Use the spell
The second example would be one less step, but we'd have to select a different target before casting. This is fine for keyboard and mouse since you can change the main target by clicking on them but for pad users, this will add more time between casts since we'd have to deselect the current target and cycle to the one we want before casting.
Take note that with auto-attack in the works, it's likely that it will be dependant on having the target selected for auto-attack to stay active. This means that if something like the 2nd example were used, a paladin with heal/support abilities would have to stop their attacks, and select a party member before using their ability since the secondary target selection would be removed to get rid of the extra Enter press. To get around that, SE would have to make specific abilities bring up a secondary target selection, which will bring us back to paladins complaining about an extra Enter press as opposed to mages.
Keeping in mind that it's actually the secondary target selection, not aoe toggle, forcing you to press Enter after selecting a spell, what would you propose for a possible spell/ability use procedure?