The problem isn't that you need to 'micro around it', the problem is the person on the receiving end needs to micro a ton to counter a unit requiring nearly zero. This means that the USF player can focus on micro'ing rifles/tanks, while forcing the opponent to do more for essentially 'free'.
Micro/Effort should be proportional; if it takes a ton of micro to pull off, it should require a ton to counter. Similarly, if it requires almost no effort, it shouldn't be very hard to avoid. This is why off-map has flares and a long delay; it's a 1-click low-effort ability, so it requires basically one click (a move command) to avoid it.
Sorry but rifle grenade withouth that hitting ground is almost nothing