Update: ASUS has provided the following update…
“Regarding the bootloader, the reason we chose to lock it is due to content providers’ requirement for DRM client devices to be as secure as possible. ASUS supports Google DRM in order to provide users with a high quality video rental experience. Also, based on our experience, users who choose to root their devices risk breaking the system completely. However, we know there is demand in the modding community to have an unlocked bootloader. Therefore, ASUS is developing an unlock tool for that community. Please do note that if you choose to unlock your device, the ASUS warranty will be void, and Google video rental will also be unavailable because the device will be no longer protected by security mechanism.” – ASUS
ASUS has started to respond to the concerns about the Transformer Prime having a locked bootloader. Earlier today we reported that ASUS had opted to secure the bootloader by putting 128-bit encryption in front of it which prevents users being able to install custom ROMs on to the device.