Things get a lot more complicated as things get bigger, an 1X1X1 ant mutated to 10 times it's normal size weighs 1,000 times heavier. So it'd barely even be able to move if its legs could even support it's now massive exoskeleton.
First off, you're confusing volume and linear measurements. Most of the time I would take "ten times its size" to mean "ten times its volume" and therefore ten times its mass. You're talking about ten times its size
linearly in each dimension. "Size" is kind of ambiguous, I guess. So I'm not sure what point you're trying to make, honestly. There are reasons why an ant couldn't be magnified in size and still function properly, and it has nothing to do with whatever it is you're saying.
One of the actual issues with a larger-sized arthropod (or any animal, really) is that surface area and volume don't quite scale the same way; this affects how plenty of things work, like muscles for sure, and probably the effectiveness of the exoskeleton and how well their organs and respiratory/vascular functions work. Another issue is that certain things just plain don't act the same at smaller and larger scales. For example, check out
this picture. An ant is small enough that water's surface tension is capable of forming individual blobs/drops bigger than the creature itself. This alone has implications for how the organism's circulatory system works (a large creature with an open circulatory system probably won't last long!), and there are probably other examples of substances having properties that don't quite scale with larger volume.
This is very relevant. Basically, as something grows in volume, the volume and mass grow proportional to the cube of the multiplier, but surface area is proportional to the square of the multiplier; mass increases faster with volume than surface area does. This creates, say, more pressure (force per unit area) on the bones and other surfaces, and also means that muscular strength doesn't scale well, and that the larger organism wouldn't be able to move
nearly as quickly, and would generally break easily.
Granted, this is all pretty academic, since the game isn't intended to be that realistic anyway.