Of which no one practically has a use for on a daily basis. I use my phone more than anyone and I can tell you that in the past year there may have been 2 times when I wanted to use data while talking on the phone (and that was to use maps to direct someone that was lost on the road). Look at the commercials for it, all of them no one would do. Would you buy flowers just as you were telling your wife you'll be home for dinner? Seriously, is there really a practical use for it?
"Hold on, I'm on the phone, but I'm gonna go surf the web" - Honestly, it's not that big of a hit for Verizon.