5 card draw hands are cooler to look at compared to Holdem hands. Plus, I'm pretty sure most other advertising still uses that kind of hand. Plus, it's hard to show a Holdem set up nicely. I also believe if you went and showed just two cards people would be more likely to relate it to Blackjack.

My opinion may not be valid though because I'm not a poker outsider, and I'm old enough that I grew up during a time when 5 card was the game people played so I'll naturally recognize a 5 card hand as a poker hand while some little internet kid might not.