The lock-in is a carrier issue. I actually run a HTC Touch Pro (a Windows Smartphone) on the Sprint network and have found it to be far more open then many of the other phones I have had. Of course, we will see what happens because for all intensive purposes much of the development in the mobile world is going to the iPhone right now and Apple is following the old MS playbook, build audience until you are relevant to developers - unlike Win Smartphones today.
As for GSM, it might have been easier today if we had done that at the time. The problem between GSM and CDMA has always been that they originally started out solving two very different problems. GSM began by trying to link very dense, small, urban areas with cellular service - like Europe where it is ubiquitous today versus CDMA which was trying to account for large swaths of area where there would be fewer users but a greater need to conserve capital by spreading towers. For the most part both have arrived at close to the same place today. However, we are still bound by the decisions of the past whether we believe they were the right ones or not.