This is a large part because for the longest time Verizon didn't have much of a smartphone choice. It was either Windows Mobile or Blackberry OS. Windows Mobile was functional and development was quite open, but the interface was clunky, closed, and not many devices had great hardware. Blackberry was the go-to for business users (remember that comic about how smartphone users see each other and themselves?), but it was also the choice on Verizon for anyone who was interested in a smartphone at all.
The Storm came out to intial hooplah, was Verizon's first attempt at launching a brand new "cool" phone. It turned out to be a complete DUD, due to the software problems.
The Droid came out with a proven OS (the G1, while a little slow showed promise), only the next iteration of it on a lot more powerful hardware and Verizon finally had a "cool" smartphone.
Look at today, Verizon has a number of Android smartphones, Motorola and Samsung with their top-tier devices, and LG with its middle-tier devices, catering to an ever-more diverse crowd looking to get their first smartphone.
Gotta hand it to Motorola and Verizon, though. The Droid launch single handedly gave not only Motorola back its name, but it also propelled Verizon forward with a line of smartphones that cater to the "rest" of the crowd, not just business users.