I've noticed the exact same thing on my 2012 SE. When I removed the glove box so I could replace the pollen filter I saw that this "filter" you refer to was in fact a piece of cotton wool like material that was stuck in place with tape. My last car had a cooled glove box which was basically a vent to allow air conditioning in and that was controlled by a on/off dial which opened and closed the vent. I assumed that this was similar and that it was broken/missing from my Antara and that someone had covered the resulting hole with this material. Having said that, when I dismantled the glove box there didn't appear to be any ducting etc to pipe air into the box via the "broken" vent. I'd be interested to know whether I have a broken vent or if like you suggest, it's a redundant piece of kit.