I do the same thing. I have WiFi at home of course but why use that when I am paying for LTE on my phone. I have not used Wifi on my phones in 3-4 years ever since moving to T-Mobile. My service is that good and even before I had unlimited, I kept Wifi off.Purposely? No.
Do I use my data because I am paying for cellular data despite having WiFi available almost everywhere?
You bet your ass I do.
UD since Christmas 2008 and I don't ever worry about my data.
And for those who may think I abuse it, I average less than 12GB a month.