that puts higher leveled tank at a much larger advantage over your av then.

No. Cooldown differences correspond to how often you can apply their capabilities in battle. The higher % of time you spend avoiding battle during your cooldown, the less you are engaged in a way that matters. This is an appropriate way to balance modules. In a way, this is also the point of the shield depletion delay, but just more compressed.

Militia LAVs don ot fulfill a very deadly role, but a more utilitarian one. They are great at disrupting a team's dominance of the map by letting you flank behind enemy lines. They can chase down tanks and harass them. Their small turrets can outrange most light infantry weapons. They are great for logisticians roaming around deploying care packages and scanning for hostile equipment and suits. Scanner LAVs are also great for early warning scouts, helping detect enemy movements where a slower scanning logi/scout on foot would be more susceptible to interception.