BMW was rejecting the luxury car's preoccupation with prestige in the 80s, at least that is what they were telling people. Perhaps they didn't pick the best car to illustrate that point, showing a vintage Duesenberg as the vehicle with hood ornament that didn't mean anything.
If you could afford one of the greatest and most exclusive cars ever sold, you should have had a better or at least more expansive answer than "it's a symbol", even in a fictional commercial based scenario. Maybe "it's a symbol of the fact I am ultra rich and was able to purchase the finest car money can buy which is why it costs more than most people's houses."
I was born the year this commercial was released so it's purely speculation, but I have a hard time believing the whole of one of these big BMWs was more than a rolling status symbol to many who bought it. The 1985 BMW 735i may not have had a huge hood emblem, but it had the status symbol under the hood, on the hood and just about everywhere else.