Air gap behind drywall on exterior brick veneer wall
It's hard to say why someone installed the framing in such a way. Most likely it was installed to (as you stated) allow for better air circulation and removal of moisture in the wall.
You should plan your project to include a means to prevent moisture and/or a way for it to escape. This can be anything from vent holes for every wall bay or spray foaming each wall cavity. The foam would have the secondary benefit of also providing a R- value by insulating your home.
Since the wall is an exterior one (I believe?) some type of insulation should be installed in order to keep the living space in your home comfortable and utility bills low. Foam is a good choice&lt;as mentioned before, but blanket insulation with a paper vapor barrier would be less costly. Check the exterior facade for vents which should be considered in your plans.