You have to remember that Verizon's best selling smartphone prior to their Droid line was BB. It's also why the X is being considered the BB killer. Before the X (Inc and Droid to lesser extents) there wasn't a good showing at Verizon, so people moving to the X statistically are going to be people moving within Verizon from one smartphone to the next meaning that most of that is coming from their BB clientele.
I bring this up because the $45 data plan is pretty much a holdover from having two tier pricing for BB contracts. Unlike the BES Push and Pull servers where that is being handled off the phone, this is completely handled between your device and your companies servers and isn't an application that has to authenticate with Verizon. So really its stupid check or for company contracts where they can get an extra couple bucks and the companies understand that to have their name on the account they have to.