I just did not want to hinder the window when it was rolling up in the track due to windows that are sticking as it is also I smoke and like to vent the smoke out the window by holding the cigarette at the top of the window. The weathertec provides less space. Just a personnal preference
I've been running with weathertec's for like 5 years now, no window issues...yeah I smoke...but the car doesn't come out in the rain, so except for washing, the windows are down, so my opinion is s$%# and I'll shut up now.