Just because I don't care about going super-fast doesn't mean I don't use my connection a lot--100GB or more per month; so mobile broadband isn't feasible. Cable, on the other hand, is. So, you think Verizon wants to push its customers (more than half of them?) to cable? (good business plan [not])
If cable returns the favor by getting people to sign up for VZW, sure it's a good business plan. It also helps VZ justify not rolling out FiOS anymore, because obviously people son't need the speed that it provides.