TL;DR
Ability to toggle agricultural tower overlays on separately from mouseover/placementWhat?
A button that toggles the coverage overlay for agricultural towers on and offWhy?
I've noticed that I pretty frequently want to see the area that one or more agricultural towers are covering, but you can only see the area of a tower that you are currently placing, that is within a blueprint, or that you are mousing over. This makes the following situations more annoying:1. Placing a new tower. Since you can only see the area of the tower you are currently placing, it makes it harder to tell where you should place it so that you don't overlap it with another tower's area. This can be worked around by blueprinting towers at the proper distance, but it's still annoying.
2. Placing belts and power poles within a tower's area. As you want to maximize the amount of area available for a tower, it's important to make sure that inserters, belts, and power poles are placed in as few 3x3 blocks as possible. Since you can't see the tower's area when placing non-tower entities, I find myself switching between mousing over the tower and placing entities to make sure that I'm not placing things in the wrong spot.
3. Placing landfill/artificial soil. If you're trying to be economical with your placement, you want to fill only the 3x3 areas that the tower can use. More generally, you don't want to place artificial soil outside the area that a tower can cover. Being able to toggle the areas on would make it easier to see what you're doing.