I'd much rather have to actually AIM, as in be able to pick my targets and such. Hack n Slash with a good aiming system can be pretty fun. Instead of trying to find a way where you don't need to trigger aiming, experiment with existing systems or come up with a new one for players to aim with. There's plenty of aiming systems around, each with their own pros and cons.
Cursor
+ pixel detect with the mouse
- single player only due to EUD usage
Dark Swarm/Dweb/MC/Halluc
+ Simple to trigger aiming systems
+ Pixel detection, though extremely limited, can be done with Swarm/Web for headshots, not practical though
- Swarm/Dweb have problems differentiating between different player's shots
- Halluc accuracy isn't perfect
- funny looking main characters (Dark Archon sniper...)
FRAGs (the one and only)
+ Can aim to the tile
+ Can differentiate between player shots
- Requires that the map continuously have room for 2 Scourges every 20x12 tiles
- Lots of triggers
Directional Detection (find what direction the user clicked in relative to the hero via 8 Scourges at the edges of the map)
+ Doesn't have the FRAGs limitation of requiring space aside from the edges of the map for the Scourges
+ Can differentiate between player shots
- Can only aim in a direction, not a specific spot, so can't shoot an enemy behind another one
- 8 Scourges can only shoot in 16 directions
- Not the most precise system
- Lots of triggers
- Still a theory, hasn't been done before to my knowledge
Ally (you are allied to the computer, forced to attack manually)
+ Easiest aiming system ever to trigger
- EXTREMELY annoying to continually have to press A and left click
None.