I agree. The problem is, today these Ram Air repop systems can cost $1000 or more. When we used to actually street race and/or drag race these cars (which is why Pontiac stuffed a 400 under the hood of a Firebird to begin with), making your own Ram Air setup cost about $20. A trip to the hardware store, couple homemade scoops, some dryer duct, you get some horsepower, about 1/10 in the 1/4 mile, and usually around 1-2 mph on a 100 mph car.
For the overpriced repop systems today, then I agree, don't install Ram Air for performance reasons, just for looks. You WILL pick up horsepower, but on a cost per hp basis, these repop systems rate very poor. Cool air to the carb is worth horsepower, always has been, always will be.
For $1000+ dollars, I'd invest in a cam, headers, and a good exhaust system. But if you want the cool factor, and a little horsepower, then get the factory Ram Air setup. If you're just looking for horsepower, you can make you're own Ram Air setup.
Just an FYI....it's a myth that the Firebird/GTO hood scoops sucked air out of the scoops, and actually cost horsepower. Pontiac moved the scoops to the leading edge of the hood for the 1969 Trans Am in order to actually get a little ram effect.