Verizon is, IMO, a conservative carrier that prefers to focus on building and improving its infrastructure rather than having the latest and greatest phones. (The reason they have the latest and greatest Android phones right now is that a lot of manufacturers want to show off high spec Android smartphones that have 4G LTE.) They, much more so than AT&T, want proof that they should support a platform and want manufacturers/mobile OS developers to come to them rather than the other way around. When Windows Phones start taking off, which I think will start happening later this year, I think we'll see Verizon step up to the plate with greater support.
I realize the above is somewhat self-serving to say, considering I'm a Verizon customer with a Windows Phone and want Windows Phone to succeed in a big way. Don't get me wrong, Verizon's current tepid attitude towards Windows Phone annoys me too. However, when you look at things objectively, historically-speaking Verizon has usually lagged in its phone lineup, due to (IMO) the aforementioned conservatism. I've really only been following smartphone goings-on since I bought my Droid 2 in December 2010, so people can correct me if I'm wrong, but when has Verizon been cutting edge in supporting a new platform? They weren't the first carrier with the iPhone and it took them 4 years to get the iPhone. They weren't the first carrier with an Android phone, and to my knowledge they didn't really start getting behind Android until the Droid 1 became a big hit. They weren't the first carrier with a webOS phone, and though they are a carrier for the Palm Pre 2 (and would have been one for the HP Pre 3), they never aggressively pursued webOS devices. Finally, they didn't have (or do have) the broad array of Blackberry devices that some other carriers have (to my knowledge they've never had a portrait slider Blackberry Torch for example). The way Verizon is handling Windows Phone right now is not inconsistent with how they've handled every other mobile OS. In time, I think we'll see Verizon give solid support to Windows Phone, and if WP does legitimately become the 3rd primary mobile OS, IMO Verizon will step up their support accordingly.