I know this post is a bit old, but it is possible for PC gamers to immediately cast ground AoEs using a macro:
Code:
/macroerror
/ac "Shadow Flare" <mo>
/ac "Shadow Flare" <t>
/ac "Shadow Flare" <f>
/ac "Shadow Flare"
/micon "Shadow Flare"
If you're mousing over a target - enemy OR friendly - this macro will immediately cast the AoE centered on your Mouseover. But if your mouse is currently over empty ground, it will instead center on your current Target, or else your Focus Target. If none of these is the case, you'll be able to manually target as usual, such as if the party's charging to safety and you want to use a similar macro to cast Sacred Soil up ahead where there's no object to target.
I use few combat macros due to queuing delays, but this is one I use. If you adopt it, you may only want 1-2 placeholders (e.g., <t> and <f>, or just <mo>), but you'll probably want to include the last /ac without any placeholder to enable manual targeting. If not, you could have a separate, non-macroed version of the AoE for manual placement. Since it'll trigger on any Target (enemy, friendly, or even neutral) there's no point in having both <t> and <tt>.