A comination of few things I would guess.texags08 said:
I guess I'm speaking more to the casual/new American fan. They wouldn't know the history of McLaren, only what they have seen recently. But point taken.
1. I think for the newer fans it does have some to do with Ricciardo. He's very popular among peoples whose first exposure was DTS.
2. Similar phenomenon when the EPL started getting popular. People wanted to pick a team to follow and didn't want to go straight to Man U and be called frontrunner. So they pick someone that isn't dominating but has potential. So throw out the teams that have won the last 12 drivers championships. That leaves Ferrari and McClaren which rolls into the next point
3. Ferrari still has a bit of front runner feel. If you're my age you maybe recall hearing their name a ton in the Schumacher days. If you're younger they probably have a more corporate/old rich white guy image. McClaren has a more plucky little guy image, and you still know them for their sports cars. Ricc plays nicely with that image as well. They're the underdog that might actually compete someday