Just tell the "old man" you are using the device for what it's meant for...it is not your fault your coworkers know squat about the device or ONLY use it for work email.
In terms of getting your own BB/phone...I for one do not trust them company-run reports. The data they spill out can be used in so many ways...for that, I no longer make personal calls with the company phone (got two cell phones for that) nor access the web for personal use (got a data card for that, with my BB having a modem option as backup).
Big brother IS watching, so why make it easy on him?
Oh btw, I just looked at my personal BB usage-it is at 500MB+, my data card (used mainly when I am in the ofc) is over 2GB. I get my work done at work-take anything that's thrown my way! I just take lots of breaks (web surf) and use my BB for many things (data-wise).