@ubergoober- I assume they picked PET because it sounds cuter and because there are no specs in the phone that match the 64 number. i think at this point the Commodore name is the selling point more than the PET. Still, your point is taken that the PET was less iconic. But I did find an interesting fact. When the PET was announced they shipped a few hundred immediately and they couldn't make more fast enough and it was backordered for several years. It was also strangely more popular outside the US as well.
At any rate, the lack of icon status for the PET might be less about the lack of sales and more about the difference in manufacturing capabilities of Commodre from the PET to the C64 which is the best selling computer in history (excluding smartphones if you count them as computers).