My Streamlines were Air-Cushion finish but my casino decks weren't. And thank you. It doesn't feel like my casino decks have any finish at all.
I think they stopped that over the years, with the Air Cushion on Streamlines. I have on me right now a red/blue pair of recently-made Streamlines (Erlanger) and they're smooth just like Aviators. They handle OK, actually, and the back is old-timey and interesting to look at. They're more common in the South than where I'm from (the Northeast) - I got mine on a visit to North Carolina, as well as some Mavericks (also regional). No major retailer of any kind sells either brand this far north of the Mason-Dixon line.
I reckon that smooth finishes are cheaper to produce than air cushion, linen, magic, etc., because you generally tend to see them on less expensive (and less popular) playing cards. A major exception would be Aladdins, and I think that's because they were specifically made to withstand the heat and humidity of Singapore. Another way of saying "air cushion finish" down there would be "filled with pockmarks that hold sweat, dirt and finger grease very nicely, making your deck handle like mud". A smooth finish combined with less water-absorbent stock make a good tropical-use deck. That's also why a non-smooth casino deck that's been used a few hours gets tossed into the sorter for canceling and repacking - they're useless at the tables after that abuse.