Not really. Most Americans go the the carrier on contract because there is no price savings by buying on contract vs off contract. Example: Buying a phone for $199 on contract with $50/month plan, or buying the same phone out right for $500 and still having to pay $50/month for a plan. That's why Americans buy on contract.
Back on topic, Verizon is the nations largest carrier but only accounts for 13-15% of WP users. So how many overall customers by percentage is that for Verizon? 1%? 2%? Verizon simply doesn't care. Switch to AT&T or TMobile (which accounts for 75% of WP users) and be happy.