The biggest thing I've seen in the lock down has been that the kernel checks the video.apk and all the drm files on the device. I wouldn't be surprised if this was put into place to prevent videos from being ripped while streaming. Then again, I always believe the MPAA and RIAA are up to stuff in secret.Yea you can root with a locked bootloader. Motorola devices are an example.
I find it a bit odd that lg wants to lock the bootloader now with the update... It's been unlocked this whole time. But that's probably not an issue... There are bootstrap apps to allow romming on locked devices.

