I too miss the feature. I'm guessing the change was made to avoid accidentally adjusting the volume when the phone is in a pocket or purse. But as the volume control was implemented pre-4.2.2 the screen had to be on too (out of standby). So if just the volume button was bumped, it wouldn't adjust the volume--I never had any problems with accidentally adjusting the volume when it wasn't in my hand (it does happen often when I hold the phone in landscape and am taking or showing pictures). The process was simple enough to do on purpose: tap the power button, then use the volume button but complex enough that it didn't just happen on its own.
As has already been suggested in another post, I think it would at least be nice to have it as an option.